PoW should actually stand for Proof of Waste. It's not even unprecedented in nature: many species will intentionally waste energy or resources to demonstrate mating fitness, as with a peacock's tail.
I'm less concerned with wasting resources (which is highly subjective), than with ecological and systemic harms. I don't care whether a terawatt is "wasted" on pointless SHA256 hashes, or calculating triangles for Yet Another Marvel Movie, so long as the externality is being paid for [0].
