Well, no -- they're not stupid. They're actually really bright folks: you can't make mistakes as huge as they made without being really bright.
I would chalk it up to hubris and greed, not stupidity.
Oh no, I chaulk it up to stupidity, trust me, most I have met are not nearly as smart as they think they are. Their egos far exceed their abilities, far more often than not. Are there some incredibly smart folks up there? Sure, but most aren’t.