In general, the specific delusions of ordinary people (IQ < 120) aren't important, because they aren't the ones who are actually affecting anything.

I'm less sure. I would have thought that they affect things indirectly at least through social transmission of beliefs, what they choose to spend their money on, and the demands they make of politicians.

Even improving the rationality and general problem awareness of smart people (120 < IQ < 135) doesn't really help, because then you get people who will expend enormous effort doing things like evangelizing atheism to the ordinary people and fighting global warming and the like.

Arguably, one should expect it to help less than improving the rationality and awareness of people with IQ < 120, just because there are 11 times as many people with IQ < 120 than there are with 120 < IQ < 135.