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...
Sometimes it's just a waste of energy because the thing is the amount of bitcoin that they are mined was just bigger than the electricity bill of the used energy by the bitcoin mining so I say that somehow it is just a waste of energy because there are a lot of kilowatts that is used by but not suitable enough for the bitcoin mining so it is kind of wasting some of our energy especially right now that the electricity supply was not enough to sustain all the needs of the people.