I'm not pretty sure but as we know bitcoin investments is more profitable than saving money in banks and I think banks are afraid in crypto cause there are a possibility that bitcoin could replace banks in the future and this is the reason why banks scared in bitcoin popularity today.
Banks are nervous about Bitcoin because they are afraid that it will spread fully in the world and the business of banks will get affected with it. Banks are under government and they also do not want to let the Bitcoin affect the banks because government has a great interest from banks.
However crypto and banks as fiat currency can go together if countries learn and adopt a system which is is using in countries where the Bitcoin is going smoothly.