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.
Bank never want something which can create trouble for it. Bitcoin like decentralised currency creat problems for it cryptocurrency provide and untraceable and uninterrupted money transaction facility and because of this many people like to use it instead of bank. Another thing is transaction through cryptocurrency are less trouble and fast and they also charge low transaction cost but transaction through bank are time taking and banks also charge high transaction cost because of tgis many people like to use cryptocurrency instead of bank and this thing affects its bitcoin profit and progress.