Can centralized exchanges ruin PoS? Its a question some of you probably asked before. CEXes for a long time have options that allow to stake coins on their platform, advanced users are probably not fooled by those because they know that staking in a wallet is a better option, but beginners who keep their coins on CEXes only, might fall for the trap. CEXes like coinbase take few % from your rewards to themselves and make staking not as profitable as it really is for their clients, but this is not what is a danger to Proof of stake, the danger is the fact that for example Coinbase custody and similair validators, are one of the biggest validators on almost every PoS network, they don't vote on any proposals but if they did, they could vote on every proposal beneficial to their companies, this of course hurts the decentralization and makes price manipulations easier. 

So... please don't stake on centalized crypto exchanges.