> You can't fix it by "not letting stupid people breed", you have to fix it through not letting people become stupid
This sentence seems to be somewhat self contradictory. Despite decades of trying to make it not so, it seems that intelligence remains primarily inherited from parents/ancestors.
Socioeconomic status, education, opportunities, etc all have no ability to improve iq. Nutrition only matters in the sense of malnutrition. So environmental factors can reduce IQ, but they cant do anything to raise it.
Attempting to "fix" it, which we have been doing in the first world for a while now, seems to be causing average intelligence to drop precipitously. the peak IQ in most nations is now firmly in the past 30-70 years back. I think we just have to give up on the idea that this is something to "fix" per se, and let people make their own choices as individuals.