Hmm. Yeah, that's hardly conclusive, but I think I was actually failing to update there. Now that you mention it, I seem to recall that both conspiracy theorists and cult victims skew toward higher IQ. I was clearly quite overconfident there.

And in any case the point is that any correlation between IQ and not being prone to getting duped like this is not perfect enough to deem anything particularly unlikely.

Wasn't the point that

intelligent, rational people with money on the line and an obvious right answer

wasn't enough, actually? That seems like a much stronger claim than "it's really hard to fool high-IQ people".