Nothing stops greed. Spam money would be on top of what they get. We are attacked from inside. You are not immune to such attacks either. But we still have means to protect Bitcoin.

More, or less but so far. Bitcoin's core team have not acted in the best interests of the project. Monero's potentially compromised contributors have stepped down, and updates require a community consensus. Not saying it's perfect but Monero seems to have less compromised devs, and has more mechanisms to ensure compromised devs don't have total control. Monero already had The Op_Return (TX_Extra) debate, and TX_Extra was reduced to counteract ordinals on Monero So far between the two it seems like Monero has the better record for now. But I'd like to hear the suggestions to counteract these problems in Bitcoin, so hopefully it can also be saved.