If a government would want that much to get bitcoin eliminated from the economy they will not target the chain or nodes or the hash rate, they will go after users.
As I said before and others did, if they would make holding cryptocurrencies a felony with mandatory 25 years, would you still use it?
That makes sense, however, there is an essential factor you seem to be missing, a single government can only enforce rules upon its citizens, if the U.S bans crypto altogether, the Russians, Chinese, Iranians and perhaps some European countries would want to buy it more than anything, banning crypto is a risky move to any government if done individually because jumping out of the train does not make it stop, it could simply keep moving and you will be left behind, you need to actually STOP the train, and that would be by "destroying" bitcoin and not just ban it.
I pretty much like Saifedean Ammous's (the author of The Bitcoin Standard) statement where he talks about killing bitcoin
The way for them to kill Bitcoin is for them to make the economic incentive to use Bitcoin irrelevant to make the demand for using Bitcoin go away at the source,, They need to offer a technology that is better than Bitcoin that can obviate the need for Bitcoin. Or, at least, they need to try.
Whenever there are incentives to using bitcoin, people will use it, some countries have up to the death penalty for smoking weed and a mandatory 10 years for owning 1 gram of weed, I have personally lived in a country with such rules, and almost half of them smoke weed on the daily.
Another problem in banning bitcoin is that in most countries law amendment can only be adopted by the national legislature and not the government. In a democracy-based country, the legislature represents the people, if the people want bitcoin you can't ban it that easily, it won't work.
I could go on and on forever explaining how banning bitcoin is not easy, in fact, a 51% attack would be easier in terms of the government's limitations, but even that might end up ugly for them.
With that said, a 51% attack by government/s is doable and we as a community should be prepared for such attacks rather than completely ignoring them, just my thought!.