Proof of work uses physically prohibitive costs to secure the blockchain and maintain a dependable ledger.

Proof of stake uses an abstract power hierarchy to attempt to secure the blockchain and maintain a dependable ledger.

Proof of work is the only concept that allows digital financial transactions to be bound to real world resources / energy. This will completely disrupt the current day financial world that is tied to abstract power.

Proof of stake will allow those with abstract power to remain in power.

If you want change, proof of work is the only option.