I dont think banks are the ones against Bitcoin. It should be the government that is against Bitcoin because they dont have control over it. The banks actually report to the government and because Bitcoin isnt doing the same, they dont like it. Because starting from tax and other things theyd have implemented or rule theyd have set, they cant. Bitcoin takes out the middle man and the government cant do nothing about it, no matter much they dislike it.
Like you read my mind on this, because clearly, the banks report to the government and the government through the asset and security agencies try to regulate the affairs of cryptocurrency all in a bid to control it just like the central banks of a country.
Seeing that the only way to control cryptocurrency and Bitcoin is by taxing hodlers and investors, the tussle now is who gets to dominate the society and become number one option for payments and transaction for the citizens.
It would be hard to gain full control of BTC or cryptocurrency because of its decentralized and P2p nature, and the only way banks will be able to survive along side the massive adoption and use of cryptocurrency, is to accept it so as they could find cryptocurrency accounts/wallets and receive as much as allow taxes of citizens to be paid with crypto currency, just like Brazil, Lugano, Britain and El Salvador are doing currently.