No test measures intelligence. A test only measures you relative to the persons that wrote the test. – loosely quoting Asimov.
2007 is ancient history now. It is an interesting graph that one might correlate with a lack of meritocratic structure in society, but I’m on the low end cause I say this without looking up and reading the study. Pretty pictures evoke emotional blabbering bias and all that.
That’s a different argument. We are talking about whether ethics is a direct factor in income. Billionaires are outliers. In a population study of millions of people, or even a survey of hundreds, billionaires aren’t going to have any bearing on the outcome.