Perhaps you are right.
But that is not what I took away from the Bell Curve nor is it observationally obvious -- if you believe the IQ metrics in that book -- which I tend to believe.
I said IQ by itself isn’t a good predictor. IQ is actually the best single predictor we have in the social sciences (not counting a person’s credit score; but that is an index of many underlying bits of information). But, by itself, IQ has low predictive power. Repeating myself, you want to use IQ in conjunction with something like conscientiousness to have a decent ability to predict. Alternately, use SAT and high school GPA in college admissions. The first measures potential and the second effort. You kind of disagree. Would you say what is the predictive power of IQ by itself.