The IQ denials and blank slate creationists are hurting exactly the people they claim they are trying to help. (Hard to tell if it is genuine, it might just be virtue signaling.)

The best thing we could be doing for disadvantaged groups is encouraging the smartest to have loads and loads of children.

Is it non-sense? I've heard many times that there a hell of a lot of problems/criticisms of IQ and that it's history is intrinsically linked with eugenics and other kinds of pseudo science. Can you link me to something supporting your claim that it's " the strongest predictor in psychology" (predictor of what... I'm not sure)?

You've heard nonsense. Please read some of the literature on intelligence research (1). Steven Pinker has also written a great book on why the ideas of the blank slate and social constructivism are purely ideological and do not hold up to analysis (2).

IQ is a very strong metric predictor of pretty much every aspect of personal success, from successful marriages to income to academic achievement to interpersonal skills. By no means is the relationship deterministic, but that isn't what we mean by predictors. (Many other psychological metrics, like the nonsensical "emotional intelligence", predict nothing when IQ is included in the mix.)

1: https://www.amazon.com/Neuroscience-Intelligence-Cambridge-F...

2: https://www.amazon.com/Blank-Slate-Modern-Denial-Nature/dp/0...

IQ is, as far as I know, a pretty strong predictor of success in life (be it financial, educational, health-wise or longevity).

Intellectualism isn't predicated on being correct. There are communist intellectuals, radfem intellectuals, etc. The major alt right intellectuals of note are people like KANTBOT, Frame Game Radio, and the bleedovers from the manosphere like Illimitable Man. I've debated with them multiple times on Twitter as a means of reaching out. They take it seriously and aren't pure ideologues.

Edit: It should also be noted that even the widely-hated Richard Spencer is not a moron. He has a Masters in Humanities from the University of Chicago, and was a PhD student in European intellectual history at Duke until he left after 2-3 years to pursue activism.

IQ has scientific value but it falls quite short of the kinds of policy and ideology that spring up around it. It's a fair guess that if someone brings up IQ in a political context as justification for their position, it's pseudoscience.