That is false. A 51% attack is only expensive to the degree to which the hashpower required to exceed 50% is obtained at negative margins.
If an attacker can collect the total 51% or more hashpower at what would be a profitable rate despite the attack, then the attack is not "definitely expensive" - no, the attack is definitely profitable and the expense falls sorely on the minority.
Or, you need to spend a lot of resources to do the attack even if it's the case that you get that money back when you succeed. And the attack is not available to you if you can't front those resources (because it's expensive rather than cheap).
There is a word for this. We call it risk.
The attack itself is unprofitable, the "profit" for Qubic is the publicity they get. (or at least that's what they're betting on)
At the height of the attack, Qubic (the company) paid people up to $3 in QUBIC for every $1 of XMR they mined through QUBIC, and they achieved around 33% of XMR's hashrate which was sufficient to mine the majority of blocks for a few hours.
If they were forced to buy back all those QUBICs they paid out, this might have cost them ~$100k/day. But thanks to the media attention it's likely that they didn't need to buy anything back and actually were able to emit more than they otherwise could have.
XMR needs to adapt -- switch to PoS, or ASICs-based POW, or a hybrid of both.
Expensive is a better fit than capital intensive, because there are massive ongoing costs to actually perform the attack, electricity for one.
If you want to understand the risks for a project, pretend you are at arms length and are being asked to fund the project 100% up-front. You'll find a huge list of risks very soon.
It's only doxxing if you can, you connect that large transaction to the attacker, but you can't unless I'm missing something.
At the height of the attack, Qubic (the company) paid people up to $3 in QUBIC for every $1 of XMR they mined through QUBIC, and they achieved around 33% of XMR's hashrate which was sufficient to mine the majority of blocks for a few hours.
If they were forced to buy back all those QUBICs they paid out, this might have cost them ~$100k/day. But thanks to the media attention it's likely that they didn't need to buy anything back and actually were able to emit more than they otherwise could have.
XMR needs to adapt -- switch to PoS, or ASICs-based POW, or a hybrid of both.