but proof of work / crypto isn't fast, and nothing makes it particularly cheap.
If we are talking fast and cheap online payments, micropayments instead of subscriptions, let's go. Too much of crypto is a solution looking for a problem (and finding ones that don't fit).
PoW only addresses a single problematic aspect of this stuff (and only reduces it, doesn't actually resolve it). It does nothing about all the other problematic aspects.
Sure, but we had that with SETI@home, and then Folding@home, and they were doing something useful with their work rather than just finding which random numbers hashed a certain way in order to get a token whose primary economic value was the assumption that "remove trust" is a useful thing in economics.
We also had a blockchain of sorts before bitcoin, and still regularly use it: it's called "git".
And we already have fast and cheap online payments. In my case this was initially in the form of paypal, then my banks got good at it more directly; in Kenya since 2005, and now more countries in the region, there's a thing called M-PESA which does much the same but works with pre-feature-phones: https://commons.wikimedia.org/wiki/File:M-Pesa_on_Nokia_1100...
I mean.. itβs a site associated with a notable VC organization.
I would rather have fast and cheap online payments than a chat bot I have to twist around until I can talk to customer service.