The example I know of, I can't talk about. What happened was likely illegal, but in the grey zone. Individuals profited to the tune of millions individually, and the transaction was in the hundreds of millions. Law enforcement never got involved, so I'll never know what a court might have decided.

However, I'd encourage you to look into hospitals, industry groups like the RIAA, family foundations like the Trump Foundation, and similar organizations. You can find your own examples easily enough.

That's not to mention non-profits hijacked for new purposes (e.g. the current move away from founding values to woke values for a few organizations that's been bugging HN commentators lately).

(And yes, I do know the difference between a 501(c)3, 501(c)6, family foundation, etc).