[mirekrusin]

Cryptocurrency exchanges seem to be solving those problems. They transact between participants in thousands per second. Bybit has no fees on deposits/withdrawals (withdrawals can be batched to avoid network fees); but network fees are not a disaster - currently network fees are: a) in 1 block 0.27 USD/tx; b) in 6 blocks 0.10 USD/tx.

[jandrese]

The fundamental problem with those exchanges is that they are sitting on your wallet. So now you're back to all of the problems with traditional banks. If someone wants to double-charge then it's up to the exchange to prevent it, the blockchain itself doesn't come into play. Worse, a great many exchanges in the past (almost all thus far) have proven to be fraudulent, incompetent, or both.