Not OP... but one big difference between PoW and PoS is that: when a PoW block is mined, there's no way to know how much hidden equipment is out there mining a

Not OP... but one big difference between PoW and PoS is that: when a PoW block is mined, there's no way to know how much hidden equipment is out there mining a parallel chain, which could suddenly appear and take over with more accumulated work. You hope the malicious actor doesn't have 51%, but there's no way to actually prove that they aren't out there. with PoS on the other hand, the set of validators who are voting on a block is known many blocks in advance. so say a malicious validator has X% of the voting power on a given block: he can't refuse to relay the other votes, because it will be obvious to all other nodes that he only speaks for X%, and what he's broadcasting lacks quorum, because the other (100-X)% votes are missing. Whereas the other (100-X)% group will be actively broadcasting that they're slashing his stake; and if (100-X) has quorum, those votes will be accepted as valid by all the nodes on the network, regardless of what the malicious actor decides to broadcast. TLDR: under PoW, silence is assumed to be absence of dissent, since number of miners out there is unknown. Whereas under PoS, silence still allows proving lack of quorum (since the voters are known well in advance), so censorship doesn't let a malicious validator legitimize their vote.