Concern about PoS

Would it be easier to perform a 51% attack on a PoS chain? Is it easier to own a PoS chain?

I saw a post from another sub talking about how PoS chains can be bought out by a government just by printing enough fiat to purchase all of the tokens on the chain. Ethereum has not switched over yet but when it does will it be protected enough by something like this? Will it be completely rid of PoW after the merge?

For Ethereum to succeed as a decentralized market it needs to have some sort of security from something like this. Or am I just too ignorant to understand?