For people with higher intelligence, their income is generally higher. The correlation is strong, the effect size is large, and the research has replicated very well. Conscientiousness also correlates strongly positively with income in a similar way.
This article seems to start with a baseline assumption of what "rich" means, but doesn't state what that assumption is. I imagine it is a pretty high bar and the article is essentially saying "successful moonshots come from all walks of life/ all IQ levels."
Taleb has written on this topic and when he did it prompted a lot of discussion. He notes that above a certain IQ threshold, the correlation becomes lower, and uses this observation to dismiss the whole correlation. However, if you look at the scatterplots he uses in his own article, you start to realize how strong the relationship really is. I can't find his article yet, might be able to find it soon...
https://thesocietypages.org/socimages/2008/02/06/correlation...
https://www.sciencedirect.com/science/article/abs/pii/S01602...
https://danielmiessler.com/blog/how-nassim-taleb-is-both-rig...
>How important is intelligence to financial success? Using the NLSY79, which tracks a large group of young U.S. baby boomers, this research shows that each point increase in IQ test scores raises income by between $234 and $616 per year after holding a variety of factors constant. Regression results suggest no statistically distinguishable relationship between IQ scores and wealth. Financial distress, such as problems paying bills, going bankrupt or reaching credit card limits, is related to IQ scores not linearly but instead in a quadratic relationship. This means higher IQ scores sometimes increase the probability of being in financial difficulty.