This feels like an Ethereum thing. Code is law, but not if it's inconvenient.
Buying private insurance leaves you open to the risk of the insurance company going bust, and, it not being mandatory means people can take the risk and then come crying to the US Treasury to solve this unknowable systemic risk that everyone actually does know about--which we're already seeing heavy pressure from people to bail out these depositors who are above the insurance limits
On the other hand, if I managed a large liquid asset portfolio and I considered having Wells Fargo provide banking services, I would know that my deposits would not be implicitly insured and that any substantial deposits were more like a loan to the bank, subject to their own illiquidity and insolvency. Because that's how banks work, except for the specific carve-out for small accounts. Thus, I would practice risk management suitable to my needs by vetting my bank(s) practices, diversifying my holdings, buying private insurance, or just hiring a professional who I could entrust to manage those things for me. Thankfully, because I have a large liquid asset portfolio available, I can afford to do that.
So at the end of the day, any large deposit I make with Wells Fargo is actually a risk-laden investment that I've made a calculation to play, just like that equity share that you bought on the stock market.
Maybe the Wells Fargo executives could start another bank, but making you lose all your money doesn't do anything to prevent that.