That said, if wealth and IQ correlates—which I’m not sure it does—you cannot say which causes which, or even if either causes the other. It is just as plausible that wealthy folks have better training taking tests which will lead to higher test scores in general, including IQ scores.
https://rpadgett.butler.edu/ps320/coursedocs/Richardson-Norg...
Now if you manage to convince me that there is a correlation, twin studies is not enough to convince me of the causation. Twin studies are controversial as they do not provide a random sample and have a number of inherit biases.
And even if you find a way to convince me that the causation is not wealth → IQ, it is still not enough to convince me that IQ causes wealth. You still have to eliminate any third variable that causes both.
This is all after you’ve convinced me that IQ is a useful and interesting metric (see nibling comments), as well as useful and unbiased, all of which is up for debate in academic studies as of yet. Good luck.
I wasn't talking about Twin studies. It is a fact that among adopted kids their intelligence correlates almost as much with their biological parents as for non adopted kids. Adopted kids is such a big group that there is no lack of data.
Why aren't those two sides of the same coin? I mean, smart people can generally figure out how to accrue and maintain wealth.
Someone will say by way of counter-example that, let's say the Kardashians are not smart. But they seem awfully clever at manipulating their publicity in ways that bring them wealth.
So it really seems to have more to do with whether one has a narrow conception of intelligence as being able to, say, find new theories in QCD or derive relativity, rather than being able to figure out how to accomplish things beneficial to themselves. Which might be D-K in effect, but who knows?