Miners are required to provable expend effort in order to become eligible to produce a block. 2nd law of thermodynamics as core security mechanism, as it cannot be reversed.
If you were to improve efficiency by routing excess heat for other purposes, it will gradually spread across the entire mining industry, and eventually you end up right where we started.
And that for something that’s almost exclusively used for speculation, because for anything else transactions costs are too high...
Hell, dont pay people, if I was mining and it was similar costs to donate the wasted energy I’d do it.
What matters is the % of miners that are honest. (See bitcoin.pdf)
High hashrate just means higher difficulty. (The difficulty controls the average time between blocks, so it's always targeting to be 10 min on average).
Also, for heating your home, mining bitcoin could end you up with a loss. For example, your heater needs an internet connection, and your heater is will become out-of-date very quickly as new more advanced bitcoin mining gear becomes available. You would also need to have your heater on 24/7 to break even, this it will cost you to turn off the mining heater due to warm weather or to cool it.
Not to mention the noise.
Honesty isn’t the issue, collusion is. The entire concept of Bitcoin assumes dishonest players.
The only real attack is for miners to combine hash power to get over 50% of the network hash rate so they can execute double spends - and even that is self defeating as doing so degrades confidence and by extension price.
They've happened on smaller chains that don't have much hash power attached to them, but even there, they're caught very quickly.
What is more secure in your view?
hashrate is absolutely necessary for high security.
Section 6 about incentives discusses about why nodes may be honest rather than collude to attack the system. This is the main pillar of bitcoin's security.
LOL... this is the most ridiculous claim I've heard about crypto-mining yet. Might as well buy a truck-full of wine glasses, break them and use the shards of broken glass to prove that I've "expended effort". Now we're using the asymmetry of time itself as a security mechanism. Come to think of it, that may be actually less wasteful than burning the electricity to mine Bitcoin.