There's a pretty strong relationship between one's self-image as a dispassionate rational thinker and the degree to which one is susceptible to fall for utterly irrational beliefs that are presented with some sort of scientific veneer

The belief in recursive intelligence explosion is a good example: only someone who thinks of themselves as a very-high-IQ hyper-rationalist could be susceptible to buy into it

If you want to fool a nerd, make long, complex, overly abstract arguments, free from the shackles of reality. Throw equations in there. Use physics analogies. Maybe a few greek words

People are subject to identity bias (you are more likely to believe a statement that seems to match your identity). If your identity is "I'm a rationalist", then you're more likely to fall for arguments that feature superficial scientific attributes.

The side joke is that a self-styled rationalist's primary mechanism for adopting beliefs remains identity reinforcement -- just like everyone else -- rather than the actual rational value of an argument.