And have a world full of Aspergers and Schizos (correlated with IQ) or some giant mutants unable to survive the next asteroid strike. I hope you get the point - we have no idea what we are doing.
Schizophrenia may (or may not) correlate on the phenotype level, but genetically, they are inverses. Genetic risk for schizophrenia lowers IQ in GCTAs, genetic correlation, and family studies. If you select for intelligence, you will get less schizophrenia, and if you select against schizophrenia, you will get more intelligence.
I mean, I'm not a proponent of the (semi-serious?) thought that "aspies are the next step in human evolution", but since I was diagnosed myself recently, I've found myself imagining what such a world would be like every once in a while...
Anyways, I'm all in favor of some forms of 'eugenics' as our knowledge about the effects increase. We've been helping our own evolution along for quite a while now, so I don't see why tinkering with our genes should somehow be completely off-limits.
This means that the choice is not "eugenic or do nothing", it's "eugenic or dysgenic".
The portion of the population that takes action to avoid living in squalor is unfit because they fail to reproduce well enough for replacement. Meanwhile, the portion of the population that fails to avoid squalor is breeding in a most exponential way. That portion was historically kept in check by death, but now has been unleashed.
So one type of person is on the way to extinction, and another type is growing without bound. Currently this means the the total population (both groups together) is shrinking, but that will change.