Proof-of-work's advantage is that it was first and is thus the standard. It's not a good standard, but it'll be around for some time. > why hasn't anybody come

Proof-of-work's advantage is that it was first and is thus the standard. It's not a good standard, but it'll be around for some time. > why hasn't anybody come up with something better In theory, anything with (artificial) scarcity could work, and not all crypto currencies are "energy credits". For example, you could trivially start a new crypto currency where all the coins already exist and from there on out it's just the energy of processing transactions. I don't think this could be tacked on to BTC as an improvement plan though. Bitcoin being an energy equivalent is just too entrenched in its DNA.