Please read up on UASF and Bitcoin. People can buy tons of mining factories, but if a very large amount of nodes start rejecting blocks and therefore the rewards, miners start to rethink their stance very fast. There is no discussion here, history proves it.
and UASF are a thing in PoS as well, if some entity/entities acquire a majority of the staked coins users can simply fork the malicious actors out. It's functionally equivalent except that it's an order of magnitude more expensive to acquire the required coins as opposed to getting the equivalent in hashpower.
