People reject this for various reasons: 1. They firmly believe IQ doesn't means anything. 2. They realize IQ means something but that it is mostly mutable (Fl

People reject this for various reasons: 1. They firmly believe IQ doesn't means anything. 2. They realize IQ means something but that it is mostly mutable (Flynn effect, etc). 3. They realize it's not especially mutable, but the tests in poor countries are unreliable. 4. They reject such possibilities because they actually believe their lifetime of propaganda that "All men are created equal" etc, etc, and so don't even give IQ much thought. 5. They don't even raise the question because it's politically or socially uncomfortable. For people in academia or in charities, this could extend to losing employment and gaining pariah status. 6. They realize demographics actually do matter but don't want to consider the fact because: 6a. Same reason as #5. 6b. It's hopeless. No one wants to just walk away from a problem. 6c. Sunk-cost fallacy. 6d. "Helping" people or even discussing "helping" people gives a sense of moral purpose, or even moral superiority. (This is Bill Gates' reason, almost assuredly.) By contrast, saying, "Well, forget Zambia, look at the whole damn world: Black people just sort-of breed poverty," is the exact opposite. To say that in polite company is very offensive.