Well in fairness, they're actually somewhat right, IQ only tends to measure specific types of intelligence related to problem solving, but not emotional intelligence or creativity, not to mention sanity.
Which is why you can wind up with virginal spergs like Ryulong who were apparently mentally functional enough to graduate college but socially inept enough that they spend years of their life edit warring on wikis over Power Rangers spellings and GamerGate.
Or why folks like Andrew Schlafly from Conservpedia (who apparently is a Harvard graduate in engineering) end up believing completely crazy stuff such as that Einstein's theory of relativity is part of some "liberal conspiracy to explain away God".