Well, I’m certainly not rich, so take this with a grain of salt, but:
I think a lot of very smart people have a definition of intelligence that is orthogonal to money-making. This is probably because, for all intents and purposes, it is. Some of the smartest people I’ve known were basically incompetent at “street” skills, and vice versa. This is especially common in fields like philosophy (which my background is in.) The level of raw intellect is often off the charts, and yet translating that into pragmatic dollars and cents seems almost impossible to them.
And so a lesson I’ve gradually learned is that entrepreneurship is not really about being smart, and being good at entrepreneurship does not indicate that someone has a high level of intelligence. It means they have certain skills that the market values, full stop. That can be technical skills, sales skills, the ability to notice and capitalize on opportunities, and so on. It doesn’t mean they are dumb, of course, but American culture has a way of lionizing business leaders and ascribing wisdom to them that they usually don’t have.
This is all long-winded way of saying that you have to decouple intelligence and success in your mind, because in the real world they are only sometimes related, unfortunately.