Indeed, that's why I said "almost free". And yeah, the acquisition of ASICs can be difficult too but not impossible for a government (they can reclaim whatever and even coordinate with other states).
It isn't impossible but something like this would be a monumental task without much benefits for the parties involved.
Through CBECI's research, China has 65% of the hashrate; but that is a sampling based on
But neverthless, the biggest obstacle to a successful long-lasting 51% attack is the energy consumption. And in a hypothetical future where nation-states has the monopoly of nuclear fusion energy production, they can use that advantage to do such attacks.
[/quote]