I, too, dislike some thing about fiat. But the real question is how is the energy usage "worth it" compared to other cryptocurrencies that wouldn't consume 20000 Twh /yr (more energy than is currently produced on earth) like Bitcoin would in this wet dream fantasy of yours?

Proof of work is the key innovation that secures the decentralized network. Thinking that something is possible with no energy is the real fantasy land of scammers (aka proof of stake)

Proof of stake has some measures of security that proof of work doesn't. Essentially, the cost to perform a consensus for a bad actor (or set of bad actors) attack might actually be higher. We've already seen centralization of mining pools on the bitcoin network, very nearly leading to 51% attacks on multiple occasions. We've also seen "Eth Classic" and several other proof of work networks suffer consensus attacks.

Of course, there are ways the proof of work model is better too. There's tradeoffs both ways. But nothing offered by cryptocurrency makes up for the enormous energy usage of proof of work at scale, so the other consensus mechanisms are the only real, sustainable models for world-wide adoption