IQ isn’t poorly correlated with income. Instead the correlation decreases as the

IQ isn’t poorly correlated with income. Instead the correlation decreases as the population under that IQ decreases, and as the utility additional wealth decreases. In other words, making more money is increasingly difficult above the obvious threshold, and the utility of it decreases.
Combined with IQ is a wealth substitute in that there is less value in wealth as IQ increases, becuase consumables decrease in utility, and risk approaches zero for smart people.
Wealth doesn’t corrlate with IQ as much as expected because trait conscientiousness is more important for accumulating wealth across the entire distribution.
More variables but IQ is a great example of the variation of incentives as IQ increases and decreases.