The reason why banks will always be against cryptocurrencies is that, since btc in its nature is a decentralized cryptocurrency and that they will not get anything from it when they allow all people to accept it.
Cryptoncurrency are decentralised in nature and this the main reason because of which many government are against of cryptocurrency. Cryptocurrency give much more privacy to their user in comparison to a normal bank. Because of this many people like to use cryptocurrency and cryptocurrency also used for international money exchange medium which is more easy to use then that of bank. Because of this many people like to use it. Cryptocurrency are also tex free and also charge low transaction cost and these things attract more people to use cryptocurrency instead of bank and this thing creates negative effect in bank progress.