That's not true at all. Bezos, for instance, is worth so much solely because Amazon is worth so much. It has nothing to do with his personal spending habits whatsoever.
Bezos is the CEO of Amazon, he can definitely take some of the credit/blame that it's worth so much and that he has such a large stake. He could cash out at any point, but he chooses not to, aka hoarding.
It would drop a bit, depending on how he handled the PR. Anyway, then he could donate 99.99% of his wealth and still have far more than any of us will ever have in our lives. But he doesn't, because he's hoarding it.