I'm not a block chain defender in any sense, but you don't have to do the idiotic proof of work crap to make block chains actually usable. You and I can sign something with a key, for instance. And the signing of signed data creates the "chain". No worthless CPU usage, no idiotic "proof of...". You know it's my key, I know it's your key, we know the order of signing. Done.

All the hype nonsense was just grifters trying to steal money. And crypto currency has absolutely no purpose whatsoever.