It's not IQ at all. It's thinking skills and also emotional maturity. Many of the nuttiest conspiritards I've met have what seems to be a very high IQ. High native intelligence makes it easier to learn stuff but it also makes it easier to rationalize insanity and think yourself into corners.

I think emotional maturity factors into it because it enables you to see past plays to your ego like "take the red pill and now you are special and know secret knowledge THEY don't want you to know!" One of the drivers of this nonsense is the ego driven desire to be special and have secret knowledge.