One might disagree on what exactly is a comparable resource. A digital currency could just as well store everyone's balance in a giant SQL database. In exchange

One might disagree on what exactly is a comparable resource. A digital currency could just as well store everyone's balance in a giant SQL database. In exchange for utter centralization the energy consumption drops to essentially zero. IIUC a PoS coin will also have much smaller energy consumption. So we have a situation where a collection of people are using huge, huge amounts of energy to speculate not only on digital assets, but on decentralized PoW digital assets.