Some people will talk it into doing something it shouldn't. The bank will get in trouble because it seduced you into making an unwise investment.
So people can try to make it do whatever; the banking backend logic won’t execute it, so it doesn’t matter. The user will just be wasting their own time.
Until of course neo-neo-web3-gpt-banks pop up that are ‘built up from the ground with ai’. But those will fail regulatory before they launch anyway.
But I personally do not want a chat interface. I find communicating with a computer via natural language to be more cumbersome than using a decent traditional interface. Perhaps some banks have worse interfaces than others, but I'm happy with what I have now.
If others want a chat interface, then great! Hopefully it can be an addition rather than a replacement.