I hear a lot about how safe bitcoin is. And 51% attacking it for a private person/ company does not make any sense and is unlikely.
But what would happen if a state wants to attack Bitcoin and uses a vast amount of compute budget (in the billions). What would happen?
Can you understand that in order to do 51% attack they would have to either buy some of the pools to redirect their power, either buy as many mining devices as needed to match the current power (let's approximate to buying as many mining devices as they are in use now)? Or, well, a mix of the two.
The thing is that even big mining companies may have to stay in the waiting list to buy the gear they need. So it would be a very slow and expensive task, not mentioning that since those billions would be taxpayers' money, if the government is a democracy, it will be the last thing (use of money) they'll approve before getting changed and the preorders canceled.