Not disagreeing with you. Successfull people tend to have IQs between 120 and 135. (citation needed) It makes sense because there are a LOT more people in that range than in the 135+ range. 120-135 is often sufficient. I suspect that something similar on the rich scale. People like Gates, Bezos and Musk were not fabulous wealthy, but they had enough to be able to bet big and take big chances.

The point they were making is that no matter how smart you are or hard you work, there are factors outside of your control that can prevent you from succeeding. That's not to say being smart or working hard doesn't improve the likelihood of success, but they're not a guarantee.