> incentives an ever increasing amount of waste that can only increase with time.

That is NOT true:

The Bitcoin block reward is cut in half every four years - an exponential decay! In the long-term it will be zero, miners will only earn transaction fees.

This means that there will be a supply vs demand market, where supply is the willingness of people to pay transaction fees, and demand is miners who consume them.

And there is only a finite willingness to pay fees! So the energy usage has a finite upper boundary through the limited supply of fees.