I forget… does PoS stand for Proof of Stake or Piece of Sh*t?
Jokes aside, the problem with PoS finally clicked for me. I used to think it was because it gave the richest people control over the protocol, which is true. But I think the main problem is that there is no opportunity cost for attempting to attack the network. You could attack the network by trying to reorganize the blockchain and double spending your coins. But you could also stake those same coins on the original chain just in case your attack fails. No opportunity cost.
With PoW, the people with the most capital still have the most power over the protocol, but there is a massive opportunity cost to an attempted attack. First, you cannot own the coin and attack the network at the same time. Any mining equipment you own could have been bitcoin instead. Also, an unsuccessful attack leaves you with a ton of electricity cost and nothing to show for it. This connection to the real world incentivizes miners remain in consensus with the rest of the network and contributing to its security instead of attacking it.