I found a video on youtube that explains why do banks hate or don't work with cryptocurrencies.
https://youtu.be/1Y7oHdnHssY
Crypto is considered as a threat to banks' existence, simply because no one can control it due to its decentralized and censorship-resistant nature. Why would banks work with crypto if they can't manipulate it at their own will? For this and many other reasons, banks will stay away from crypto as much as possible.
I wouldn't worry about banks' support towards crypto since it was never been about replacing the current monetary system. Fiat will eventually evolve into a CBDC, making banks even more powerful than usual. What's important is that crypto stays decentralized so that it could stand the test of time. As long as it stays that way, it'll live alongside Fiat for generations. Just my thoughts
Why did you decide that cryptocurrency threatens the existence of the banking system?
Decentralized finance threatens not the banks, but the authorities who exercise control over everyone. Banks will work with crypto currency if it is profitable and safe for them, while this is not the case.
CBDC is not a cryptocurrency, it is just a digital Fiat that the authorities can print as much as they want and will also control everyone through it.