Honestly, given that your bank most likely is processing your data using AI/LLMs anyway (after all, credit scores were one of the first applications of "big data" and "machine intelligence", back when that was mostly logistic regression over a handful of data points), why should I not also reap the benefits of that?

I think until proven otherwise, it's fair to consider financial data public information at this point. If we want to change that, I think it'll take way more than just not granting ChatGPT access to your bank account (although it'll definitely include it).