Proof of work is not even scalable to the level of current bank transactions. Ethereum network didn't have enough compute to clear the backlog created by some niche cat NFT "game" a few years ago when people still gave a shit about NFTs.
Limited purchasing power of the poor and middle class is a political problem, not a problem solved by tech, no matter what crypto gurus and tech messiahs will tell you. The most prolific crypto miners are the ones that already have more "traditional" capital to invest. So crypto is not solving the wealth divide, it is just making it worse.
I hate banks as much as anyone, but crypto is not the solution.