Earlier quoted context omitted.
>Hopefully sophisticated investors who should’ve known better. You mean like your retirement fund manager?
“Sophisticated” doing a lot of lifting in this case. Very aspirational. If you’re buying single named securities without any due diligence, you deserve the returns you encounter. That’s your job! No one index investing is going to feel this in a material capacity. Depositors will be made “whole enough”, and an irresponsible bank got blown out and dismantled. The system worked. If there was fraud, regardless of crimin…
I don't quite understand your position on insider trading. The idea behind making it a crime is that no matter how "sophisticated" an outsider is, they don't have insiders' non-public information. Insiders can profit from the information gap between them and the people they sell their shares to. There's certainly disagreement about how to ban insider trading while making it possible for officers of the company to trade at all, but the basis of the law is that no amount of due diligence can undo that imbalance in information.
It sounds like you're saying that one might decide, as an individual, that the system is unfair or imperfect or corrupt, and decide to diversify. That's probably good advice. But that is a practical measure that doesn't really address the problem being discussed.