In short, the answer is no. Banks and crypto are not opposites, but they have different purposes and ways of working. Banks are traditional financial institutions that provide services such as savings, loans, and money transfers. Crypto is a digital currency that uses blockchain technology.
If you say they have different purposes, I wouldn’t be in very much agreement with you but, when you look at it from the way it’s operates, there you can find some real difference.
I suppose your contest to banks as in the OP is you referring to fiat currency otherwise, if your referring banks as a financial institution, then you would be making a lot of mistakes trying to put cryptos and banks in contrast.
Having the above in view, fiat and cryptos are both currencies and means to finance. Hence, it’s hard for them having different purposes.
When it comes to means of operation, there remains a difference between a decentralized system and centralized systems. While one is more privacy concern and can serve variety of purposes, the other is limited by boundaries.
Fiats and cryptos aren’t meant to be exclusive, I always tend to view them for a fill up on the limitations of the other.