What are the ways to decentralize network hashrate?

Is there no way to introduce some kind of mining luck penalty for entities that control more than 30% of the network hashrate?

So miners have no incentive to join a mining pool that controls more than 30%?

There is no way to decentralize something like PoW or PoS which is designed to centralize. PoW is much better but still fundamentally flawed especially on transparent chains.