[TeMPOraL]

> The cost of energy is minuscule compared to alternative means of achieving the same: vaults, guards, banks, lawyers, etc.

That's only because Bitcoin is still relatively insignificant blip in the world of trade, mostly a pastime for gamblers and scammers. It's footprint is actually absurdly huge compared to value it provides.

The real problem is scaling. Vaults, guards, banks, lawyers scale somewhere around O(n) to O(n logn) with the size of the market. Bitcoin's proof of work - the means of securing it - scales, to the best of my understanding, as O(n!) with the number of miners. That's not something you can run a global economy on.