51% attack will be so costly that only a government of a big country can pull this off to destroy BTC
Well it if costly for them why would they pulled that stunt? Doesn't make sense, also I don't think that the resources will be enough to go long term.
a 51% attack that double spends appears to violate the Computer Fraud and Abuse Act. i think even a mere censorship attack would qualify based on that legal theory.
whether it's enforceable is another matter. it carries a prison sentence of up to 10 years per count, and victims could sue for damages, but this is all theoretical. it's never been done, and the legal theory has never been tested in court. i assume the discovery process would be an absolute nightmare.
I have big doubts that anyone would bother to investigate a censorship attack, the authorities wouldn't even clearly see who is the victim, who is the culprit, what was the damage, and Bitcoin is a decentralized network, not a company that can go to court. In case with double spend, there will be a clear victim - an exchange or other service that lost millions of dollars worth of coins, and the attacker that made and then reversed a transaction.
I agree, I don't think that any governing body will investigate 51% attack unless a country was really affected by it to consider this as an economic sabotage. Exchanges will surely be the victim here and might chase and sue the bad actors behind in the court in case of double spend.
For all intent and purposes, lets look at
Bitcoin Gold Blockchain Hit by 51% Attack Leading to $70K Double Spend