PoW work is never wasted, it adds to the security of the network. The flaw in my opinion is not pow mining, it is that given the rise of bitcoin price there is already too much security. The mining rewards should have fallen of faster than they do and we now are in a strange situation where the price is high even though adoption is still low and huge rewards are set out to support the network.

This design in bitcoin was designed to support the early growth when success of the technology was anything but clear. Now it is a big waste and I am looking forward to the next block-reward halvings that will help but that come a bit too late down the road.