You're right that it is an axiom: "a statement or proposition which is regarded as being established, accepted, or self-evidently true." There's nothing "hard"

You're right that it is an axiom: "a statement or proposition which is regarded as being established, accepted, or self-evidently true." There's nothing "hard" about money that requires a nation's worth of energy simply to continue to exist. Proof of stake isn't fundamentally flawed, and proof of work isn't perfect. They both have many variations, and there's certainly many more to explore yet. The only free lunch I see people pining for is the idea that they can squat on a wasteful, moribund asset, expecting it to be worth much more in the future.