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.
Many banks dislike bitcoin because of its decentralised, which creates trouble for banks and affects their profit and progress. Many country ban bitcoin in their country because their nation banks are against of bitcoin. Bitcoin provide their its user an untraceable and uninterrupted money transaction facility. In order to complete an transaction through bitcoin their is no need to give full information of sender or receiver and because of this many people like to use it in comparison to bank. And bitcoin fast, secure transaction facility also attract many people use it. And Because of this national bank loose their profits.