Big banks need to change their minds fast, otherwise they will crash, as people are already migrating to digital new banks much more friendly to crypto currency than the old ones.
If you sweep your funds into a cryptocurrency account, what cryptocurrency are you going to use to hold your funds?
I like that saying: never put all your eggs on the same basket. That is a good thought to remember when you want to invest your money. I see no reason to invest only in btc, although the biggest part of the crypto budget must be on it.
It's better to check what are the up trend altcoins and share a percentage of your budget with them.