Bitcoin's Security Budget Issue: Problems, Solutions and Myths Debunked
budget.day
budget.day
If there is a certain latentcy/bandwidth/storage/decentralization tradeoff with block sizes, then we ought to design cryptocurrencies to make the most of this tradeoff with respect to predictable low/high demand.
What you describe is what is done with countless blockchains already, including the example I gave. This is a solved problem.
Solana: let’s make it so that enthusiast grade computers and internet connectivity by 2024’s high range standard works. Sometimes. But keep pushing.
This decentralizes transaction processing and arbitrary code execution.
Client upgrades and hard forks are largely centralized. This isn’t one and the same with the transaction processing nodes compared to bitcoin.
Saying centralized without context is reductive and doesn’t tell much though. I would like all aspects less centralized though.
Profit driven mining companies are honestly kind of not a very good force and push for lots of weird scams to encourage mining like memecoins on BTC or "dog pictures", and also regularly mine just pump and dump alts (including the biggest BTC miners).
Mining should just be as distributed as possible and integrated into stranded power likely generating a small if any profit.
Blocks are empty because people decided that bitcoin was not a feasible means of transaction nearly a decade ago during the blocksize war.
The piece is not garbage, but a thoughtful introduction to a problem that's approaching inexorably.
Why should this be the goal?
I'm sure miners would love to see their revenue never decrease, but this isn't a problem for users or for the security of the network. Block reward does not need to remain at or above current levels forever; it just needs to remain predictable from block to block. Difficulty adjustment works both up and down, even if we've only seen it go up so far. The 51% risk is overblown - the network is significantly overprotected right now, and we could stand to lose a few orders of magnitude without jeopardizing security/availability. Plus, it might even placate the energy consumption doomsayers.
As GP notes, empty blocks are now common, which is in fact a bigger risk in a low-subsidy environment. Maybe we should instead reduce minrelaytxfee to 0.1 sat/vB to incentivize full blocks.
The actual solution to the security budget is to make a ton of payments in a (blindly) merge-mined sidechain and ensure those transactions there pay lower fees but those lower fees get aggregated into a single high-fee paid on Bitcoin. That is the Drivechain proposal: https://drivechain.xyz/.
Drivechain is an idiotic proposal to just give total control of the network to miners. Atomic swaps already enable the same thing, except without a wealth transfer to miners.
I get it, it's fine to not want to learn things, but that comes with the burden of not being allowed to comment on it.
Apparently you have not carefully read my criticism of the big block proposal above. I've included some numbers. A proper response would have to address those. But thank you for trying.
The numbers you have included are just arbitrary prices you are guessing. The price of bitcoin fees is not totally elastic, because the demand for bitcoin transactions is based on network effects. So the total demand increases with the block size at a rate greater than the supply.
Specifically some of the political discussions lately feel like they could use better dashboards. The call to action at the end of this article with three main solutions called out now has some context in several dimensions (time, space, monetary).
The doge.gov website for instance would've been a prime candidate for that, like some sort of observablehq.com ability slice and dice a data dashboard. But then you also have to be able to trust the data I suppose.
I think the budget day article does a good job contextualizing all its data and guides you through it intuitively. It's more like an essay that has the dashboard woven into it. In 4 months if the fees change or BTC price changes etc. the article is still relatively up to date.
So I think that project2025 website maybe does the dashboard thing that never really took off. There's lots of open data or government data sites that have dashboards but seem like they became data portals. They never became a broad format for explanation or persuasion.
A standard dashboard might be better than nothing. But the tufte-ian dashboard seems like it would have more affordances like this budget day does.
One way to think about it is to relate the total fees to the value of your transaction. If fees in blocks with a block height above the block with your transaction total $10000 (the security budget) then an attacker might be willing to spend that amount on energy to rewrite the chain. Another way to think about it is to relate the security budget to all recent transactions, assuming the attacker is the counter party to all of them (worst case).
In either case, there is no obviously correct answer to how high the security budget has to be on a per-block basis. The question is how long you're willing to wait for the security budget to accumulate and cover your transaction. If the block subsidy decreases and fees don't rise to replace them, then settlement time increases. Don't hand out goods to a counter party if the value of your transaction hasn't at least been met by the security budget. No need to wait longer than the point at which the value of all transactions of the block which includes your transaction has been exceeded by the security budget. An attacker would be losing money at that point if they tried to scam you.
There were several attempts of merging important BIPs, which were rejected because some developers thought it wasn't in line with the direction their employer wanted.
Trying to maximize mining profit is adversarial with the end users and makes using bitcoin unattractive.
Also, the firms who take the other side of that bet talk, and you aren't going to be able to get tens of billions of dollars of derivatives without people figuring out what you're doing and acting against you.
You can make those bets on regulated exchanges, thanks to bitcoin-trust ETFs. IBIT is the largset of those, with $74bn assets under management, and it looks like options contracts are available. Correlated bets would also be easily available with companies like Microstrategy.
I think the biggest risk to such a move would be legal, since executing a demonstration 51% attack would plausibly result in a market manipulation investigation.
Second, the system only seems vulnerable if you ignore economic incentives. A 51% attack isn't just technically difficult - it's economically irrational. Pulling it off would cost billions, and even then, there's no clear way to profit from it. The only scenario where it makes sense is a non-economic actor (e.g. a hostile government) aiming to disrupt Bitcoin. But even then, that investment could be neutralized by a fork that tweaks the mining algorithm, instantly rendering the attacker's hardware obsolete.
Also, what alternative "place to keep wealth" is truly immune to a nation-state actor? Cryptocurrency is actually unique in that, with something like a brainwallet, seizure can be made practically impossible.
1. The $4B "Cost" Is Fundamentally Misinterpreted:
* It's Not a "Cost" Like Buying an Asset: The $4B figure (if accurate) typically refers to the theoretical short-term cost to rent sufficient hashrate to perform a temporary attack. This does not mean you can "buy" control of Bitcoin for $4B.
* Acquisition Cost vs. Rental Cost: Actually acquiring the hardware (ASICs) and infrastructure (data centers, power contracts) needed to permanently threaten the network would cost orders of magnitude more – potentially tens or even hundreds of billions of dollars – and take years. This hardware market is finite and competitive.
* Sustained Cost Ignored: A meaningful attack requires sustained hashrate dominance for a significant time (days/weeks), not just a single block. The ongoing electricity and operational costs for this would be astronomical, likely exceeding the initial "rental" figure many times over during the attack period.
2. Market Cap Does Not Equal "Cost to Attack":
* Apples vs. Oranges: Comparing market cap (the total value of all coins) to attack cost is invalid. Market cap reflects speculative value based on future utility and scarcity. Attack cost is a technical and operational expenditure.
* You Don't "Steal" the Market Cap: Successfully executing a 51% attack does not grant the attacker control over the $2T in Bitcoin. At best, it allows double-spending their own coins or censoring some transactions temporarily. The vast majority of coins remain secured in wallets the attacker cannot access.
* Attack Destroys Value, Not Captures It: A successful attack would catastrophically undermine confidence in Bitcoin, causing its price (and thus market cap) to collapse rapidly. The attacker would destroy the very value they supposedly spent $4B to "access," making the attack economically irrational unless motivated by non-financial reasons (e.g., state-level sabotage).
3. Game Theory & Miner Incentives Are Ignored:
* Miners are Deeply Invested: Miners have billions invested in hardware, facilities, and operations. Their business model relies on Bitcoin having value. Deliberately attacking the network destroys their investment and future income. Honest mining is vastly more profitable long-term.
* Community Defense: The Bitcoin community would detect an attack in progress. Exchanges, businesses, and node operators would coordinate to reject the attacker's chain via a "hard fork," rendering the attack useless and isolating the attacker's resources. The attacker loses everything.
* Security Scales with Value: Bitcoin's security model is designed so that as the value (and thus reward for attacking) increases, the cost of attacking increases even more due to competition driving up hashrate and hardware costs. The $4B figure is a snapshot; a rising price attracts more miners, pushing attack costs higher.
4. Practical Realities Make It Near-Impossible:
* Hashrate Distribution: Bitcoin's hashrate is geographically distributed across thousands of entities and jurisdictions. Coordinating or coercing enough miners to collude for an attack is logistically and politically infeasible.
* Resource Mobilization: Amassing the physical resources (ASICs, power, data centers) secretly and quickly enough to launch a surprise attack without alerting the network is practically impossible at Bitcoin's scale.
* State Actor? Even if a powerful nation-state attempted this (ignoring cost), the detection risk is high, the economic fallout would be global, and the community fork defense would likely succeed, making it a costly failure.
Conclusion: The comparison between Bitcoin's market cap and a theoretical, misinterpreted attack cost fundamentally misunderstands Bitcoin's security model, economics, and game theory. The $4B figure drastically understates the real-world cost and ignores the catastrophic economic consequences for the attacker. Bitcoin's security lies not in it being impossible to temporarily disrupt, but in the immense, sustained, and economically irrational cost required to mount a meaningful and lasting attack, coupled with the network's robust defenses and stakeholder incentives. The imbalance perceived is an illusion created by comparing two fundamentally different metrics.
Competitive ASIC miners are manufactured by only a few companies. It's not inconceivable that they could use TC to lock them to specific pools or simply refuse to sell ASICs to the general public.
The average time to mine a block is 10 minutes so let’s convert our J spent per block for one miner : 33346010 = 2,000,400. With about 4m of these, that’s about 8 trillion joules per block. Now if we divide that by 3.6m to get kWh, we’re back around ~2m kWh per block. Texas is about 15 cents per kWh so we get about $300k spent per block.
To 51% attack, we’d need to spend a little bit more than that. With full competition, and an attempt to mine empty blocks, it would take about $48m to attack the network for a day (144 blocks). And that’s just back of the envelope math.
Realistically, not everyone has the latest and greatest in mining equipment and probably burn more money with less efficient miners.
And all this is on top of the capex required to acquire 4m S21s, which would be around $10B at around $3k a pop.
[1] https://ycharts.com/indicators/bitcoin_network_hash_rate
> Tail emission: stop halvings and allow infinite inflation
The reality that no one wants to talk about is that Bitcoin is screwed and there's no way out of it, because of bad fundamental design.
Increasing block size will only work to solve the problem of Bitcoin's Security Budget if it brings in more usage/transactions; but Bitcoin's adherence to its traditionalist values is what led to the creation of a billion other cryptocurrencies to solve this exact problem, they do solve it, and they experience significantly higher transaction volume as a result. There's no evidence that volume is going to come back to Bitcoin. On the contrary; volume is down on Bitcoin, significantly, the usage these days looks more like 2018/2019. Its not coming back.
It also doesn't help that crypto, in general, is a dying technology.
> Burning dormant coins (e.g., Satoshi’s)
The fact that this is suggested, even as the last possible solution, should scream volumes about where this project and Bitcoin is at. This possibility shouldn't even be on this list. Not only would it do all the things the article says it would do (violate property rights, incite riots); it wouldn't even solve the problem. It would just buy a few years of time.
But as long as the miners have to buy their mining equipment using inflationary US Dollars; they're screwed. The only thing that would keep it going is growth in the usage of the currency, but (1) all growth stops eventually, and (2) even if it didn't, Bitcoin seems designed from day one to inhibit its own growth, because it was designed by an idiot crypto-maxy anarchist teenager who made the predictable software engineer mistake of thinking skill in compsci makes you skilled at everything.
How much does the security budget need to be?
When is it projected to drop below that?
The closest they come to addressing that seems to be a quote saying "We might have only two halvings left before this becomes a serious issue."
So 8 years-ish?
The original intention was to fund the network entirely off fees eventually. I don't think there was a stated expectation of block size, but it was intended to be made larger at some point.
Before coming up with specific solutions to the cost of securing the network I would think that evaluating what the acceptable range of cost/security should be would be the first starting point.
I feel they also neglect a realistic evaluation of the likelihood of a 51% attack. As soon as someone interferes with the network by 51% attack, everybody knows that it has happened. What countermeasures might be deployed?
While a miner confirming a block is like a rubber stamp from an auditor, there is nothing to stop other people from checking their work. If there are shenanigans they can be spotted, if a genuine 51% attack were to happen people would be highly motivated to counter it. That may involve bringing more compute to the network, or even changing the protocol. Ultimately the network is decided by the consensus of the users. Accepting signed blocks is the consensus. Because of the scale required to do a 51% attack on BitCoin it would almost certainly be detectable who was doing it. Under an attack people would be prepared to swiftly agree to some rule to exclude the attacker, the alternative is just two severe. You could think of it as a fork or you could think of the attackers version as the fork. You could have anything from, 'Today we stop accepting blocks from that pool over there', to 'From now until this mess is resolved, Kate confirms all blocks with her private key, We trust Kate, she's nice' The mitigation could be prosaic or fantastic, it doesn't matter, the thing that people agree upon will be the new chain. A fallback proof of work algorithm that requires more generalised hardware would work well. In case of attack, switch back to GPUs and a lower hash rate on a newer algorithm. ASICs become redundant and the network redistributes to whoever is supplying the GPUs. Then to do a 51% attack the attacker must not only have enough to 51% the ASIC hash rate, but have in reserve more GPUs than the rest of the world can bring to bear at short notice to 51% the fallback method.
I don't know but I expect it to be proportional to market cap, not getting cut in half forever.
>The original intention was to fund the network entirely off fees eventually.
I think this was a half-baked idea from satoshi. My theory is that the bitcoin distribution was chosen to avoid having to decide on any "arbitrary" emission schedule. Bitcoin basically acts an experiment to determine what level of coinbase reward is safe, through bisection.
>if a genuine 51% attack were to happen people would be highly motivated to counter it. That may involve bringing more compute to the network, or even changing the protocol.
Who? Just bitcoin users in general? There is no group that stands to gain, it's sort of a tragedy of the commons situation.
Bitcoin's security is tied to ASIC hardware. You can't just spin up a couple desktops at home to protect the network anymore.
>A fallback proof of work algorithm that requires more generalised hardware would work well.
I think monero already does this. Look up "RandomX" it is amazing to read about. But the problem is that these CPU-mined coins are even easier to attack because you can easily rent hardware or use a botnet to do a 51% attack. Whereas with bitcoin you need to buy a bunch of ASICs which would be devalued by such an attack.
>Ultimately the network is decided by the consensus of the users. Accepting signed blocks is the consensus.
I was going to write a long response to this, but in a nutshell classical consensus and PoS sucks.
There's the famous paper "The Economic Limits of Bitcoin and the Blockchain" [0, 1] answering this question. Bottom line: huge.
> Nakamoto’s novel form of trust faces serious economic limits. It is unusually expensive in absolute terms relative to the stakes involved, and its expense scales linearly with the stakes involved. [...] if permissionless consensus in its pure form were to become a more important part of the global economic and financial system than it has been to date, then the costs of securing the trust would become preposterous — more than all of global GDP in some scenarios.
David Rosenthal has good introductory posts on this [2] in his excellent blog.
[0] Original 2018 version: https://www.nber.org/papers/w24717
[1] Updated 2024 version [pdf]: https://socialsciences.uchicago.edu/sites/default/files/2024...
[2] https://blog.dshr.org/2025/05/who-is-mining-bitcoin.html
https://blog.dshr.org/2018/06/cryptocurrencies-have-limits.h...
https://blog.dshr.org/2019/02/the-economics-of-bitcoin-trans...
Any way you slice it there's still a centralization of power of when to activate any of these defense mechanisms.
They can either double spend by reversing the chain (in which case they’d have to accumulate enough bitcoin for to make it worthwhile in the first place) or they can mine empty blocks and prevent any transactions from being processed.