the problem is as a means of cash it’s inferior to existing systems in pretty much every dimension. more expensive, slower, more risk, higher volatility. the cash story for crypto is not good.
Bitcoin CAN be used as a store of wealth and the slowness actually makes it better as the slowness is part of the same process that makes it safer, harder to hack/takeover, and gives it value.
You should not look at all crypto as one thing.