Or higher income leads to higher IQs because of better education, nutrition and opportunities.

That data is in fact orthogonal to my point, for two reasons:

1. When we are talking about wealth and power that actually can influence the quality of the lives of many other people, we are talking about way less than 0.01% of the population. Those people aren't covered in this survey, and even if they were it would be impossible to identify on an axis spanning 0-100%.

2. Your linked article talks about income. People with significant wealth and power frequently have ordinary or below-ordinary income, for tax reasons.