Bank of America has an estimated 67 million customers. Assuming $250k per person, and I've got the number of zeros right, that's $16 trillion ($16,750,000,000,000) in liability if they were to go down, enough to sink FDIC.
I think you got the math wrong, because I'm 100% sure not all 67million customers have $250,000 in their accounts. Being that 56% of Americans can't cover $1,000 expense[0], and most people with >$100k assuredly have their money in assets rather than cash, I think your math is way, way, way off.
[0]: https://www.cnbc.com/2022/01/19/56percent-of-americans-cant-...