If government agencies can hack into and disable secured nuclear facilities (this happened... yesterday), I dont see why it would be "impossible" to attack random Bitcoin mining facilities. When state level intelligence agencies are your adversary, I wouldn't assume you can "just patch it" either.
Oh, it's possible. You hack into, what? One? A couple? But it does not scale up like that. Do you really honestly think you can reach 51% like that? Besides, yes, you can just patch the vulnerabilities. Contrary to popular belief, vulns are not plentiful and are not cheap. Using one kind of burns it. So it would be a _very_ stupid usage of vulns.
Precisely the decentralized nature of BTC makes it impossible to shut it down exactly the same way you shut down a nuclear power plant.
And ok, you 51% the network. Then what? You can't create BTC's or change the rules of the game dramatically, without a fork. so the people on the original network are kind of... meh, at your attack. You could double spend but you need to own the coins you spend, so you shaft a couple of people. What then? I do not think that would kill it, there are cryptos that were 51%'ed (looking at ETH classic) and are still alive and chugging along.
