Not a dumb question at all.

Proof of Work requires real expenditure of energy as the proof that you’ve done the required job to secure transactions history. Energy expenditure can’t be faked because nobody can mess with the laws of thermodynamics.

Proof of Stake requires the deployment of large sums of capital as collateral to allow participants to secure transactions history. There’s no anchor in the real world and as a pure software consensus mechanism it is prone to manipulation.

Hope this helps.