It's still better to have a variety of assets but I think one thing that should be explained about bitcoin is there isn't a high starting minimum balance. People who can't afford to open up a savings account can open an account on a bitcoin exchange first for example and then learn how to transfer that to other storage.
I do use banks for cashing in and out. Also I use banks for savings with interest rate, it is good and passive.
Only keep crypto you can afford to lose. Preferably you'd have most of your "savings" in other forms instead of justcash in banks. You are just losing money keeping your money in there. For example the highest interest I've seen in my country that don't lock the money in for 5+ years is 0.25%/annum with a minimum daily balance of $983- the inflation rate is around 3%.