You can have a bank working on top of a cryptocurrency network. It's the same except that everything is transparent + you don't need a bank if you don't want one.
Essentially all these services and exchange that offer bitcoin wallets are like banks. I think they have been the main way to get and hold bitcoin since the early days, I would guess normal standalone wallets are in the minority when it comes to the amount of users. For quantity stored maybe not so much.