I don’t think banks are the ones against Bitcoin. It should be the government that is against Bitcoin because they don’t have control over it. The banks actually report to the government and because Bitcoin isn’t doing the same, they don’t like it. Because starting from tax and other things they’d have implemented or rule they’d have set, they can’t. Bitcoin takes out the middle man and the government can’t do nothing about it, no matter much they dislike it.
Banks are against cryptocurrencies and Bitcoin adoption because if everybody switches to Bitcoin will the banks exist? Can you tell me that since the invention of Bitcoin that ain't there people who are no longer interested in keeping their money with the banks but rather prefer to use the money to buy Bitcoin and hold it instead of saving it with the bank.
Banks will continue to exist because let's be honest, we'll never have a fiat-free society. What we need to aim for is having bitcoin as a reliable alternative to fiat currencies and banks. Starting these wars banks against cryptocurrencies for me is pointless because they can perfectly coexist and people will have the choice to use one service or the other.