Because they are scared out of their minds that crypto is going to en the central bank and gov controlling game. They want to build their own centralized block chain base platforms because what else can they do? Crypto is about to knock them out of their game.
It's also why you constantly see attacks on BTC an crypto in general. So they can swoop in and claim to solve all these problems with "regulation" of the crypto space. Obviously that's not going to happen, but it is amusing seeing the vultures in the banking industry scratch and claw to try an remain relevant. They are going the way of the dinosaurs.