> Let's add up the carbon footprint of the traditional financial ecosystem, in whole. I think once all the externalities are factored in (including things like minting and handling physical cash and coin), doing it all on a computer makes more sense even if POW is energy intensive.

Cryptocurrency didn't event the idea of using computer ledgers instead of physical cash and doesn't get to take credit for it. There are dozens of ways to pay by computer that don't involve wasteful PoW.

> Converting energy into economic value is the opposite of waste.

Agreed, but I still don't see the value being produced by the cryptocurrency system. The value (not price, but value) that it delivers compared to traditional visa/mastercard/etc. seems marginal at best (and perhaps even negative once you account for the externalities that cryptocurrency-enabled crime imposes).