Putting your money in a bank is just a conditional IOU from the bank to you. In other words, it's no longer your money and they don't have to give it back to you if they don't want to. Monero solves this.
Worth noting though. That over the last 20 years or so. So many banks have merged in all but name.
Per bank only applies to the owning company registered with the FDA.
So dividing wealth over 85k into multiple banks is getting more and more impossible. Not to mention, the same merging of banks puts the whole nation fiscal security at risk in the event of a collapse.
We supposedly have $250k, but the FDIC has 1% of the money they say they cover. A very few big banks or many small banks fail and the FDIC is broke and the money would have to be printed by the fed and cause hyperinflation. I bet your regulator has only a small percent too.