It is a wasting because it could be done with staking, that way the could shouldn't need miners. And i think this is why ETH is moving to PoS.
And it's a waste if the energy cost is bigger than the mined coins...
Actually I always saw it as "freezing" energy, you can always re-spend it later on and keep it circling, yeah bitcoin uses this much energy as of now but then in the future you can always keep that energy working.
Or maybe I just don't understand the true benefit of PoS