The main reason (why banks don't like btc and other cryptos) is the loss of profits.
Transactions made via blockchain kills transactions made via banks.
But the topic is essential! It should be upped!
of course banks do not like bitcoin and even attack bitcoin, banks around the world can go bankrupt in total if bitcoin currencies dominate the world, we see many conveniences offered by cryptocurrency, the process is not complicated there is no barrier between countries, and its secrecy is guaranteed and surely it can't be regulated or controlled by any country, that's what all banks in the world are worried about and of course the bank doesn't want to lose their money tree.