A while back I googled the number of transactions per second for the various types of payments in the US, and it came to less than 100K tx/sec, including credit, debit, cash, checks, wires, and ACH.
Rollups on Ethereum today can handle a couple thousand tx/sec, and the sharding system they have planned will boost that by about a factor of 200. These systems are somewhat centralized for block production but fully decentralized for verification.
Having had to spend time more than once physically visiting bank branches to send wires, or wait for days to get checks to clear from one bank to another, I'm not convinced that today's solutions are all that impressive. They don't exactly seem simple, either.
Except 500x is not nearly enough. It may be enough to temporarily drop the fees but it a post-blockchain world where everybody does dozens of blockchain transactions a day, be it to play a game or buy a coffee or ride the subway, it's not ever close to being sufficient. Your scaling factor needs to be millions of times better.
So what's the solution? Even more complexity on top of this ridiculous Rube Goldberg machine? All that to emulate solutions that already exist and already work well and vastly more efficiently?
Why?
[1] https://vitalik.ca/general/2021/01/05/rollup.html