I don't think that's really as much of a misconception as you appear to think. Most folks understand these folks are more power hungry than money hungry.

I saw a recent interview with Bernie Sanders and they were asking him about how Elon Musk doesn't really want more money (i.e. an extremely small amount of his net worth is in cash). Sanders replied along the lines of "Sure, I agree with that, but the alternative is worse. Musk wants to buy elections, he wants to muscle his way into government in completely unelected positions, just to enforce his will on the rest of us."