First - sample sizes get smaller and smaller as you approach the edges. Law of low numbers begins to materialize.

Secondly - there’s no point in optimizing around the edge cases. As a whole it’s pretty reliable.

Everything is complicated isn’t a good reason to not take more effective action than what’s done today which is destructive and cruel. Letting stupid people, who are stupid by no fault of their own, fend for themselves and calling that liberty is why we have such poor outcomes for these people.

I don't have any specific opinions here other than the limitations of the IQ/income correlation. For instance: trying to infer cognitive ability from income would be a deeply stupid thing to do. (I don't see anyone suggesting that).