Whilst I agree with what you wrote in the above about various reasons to believe in extraordinary things, there's no evidence the ratio of UFO believers amongst the intelligence community is any higher than anywhere else. The seemingly 'high ratio' is an observer error created by media coverage and the ufologist college pushing for that coverage. What seems obvious is that those from the IC who have "come out of the closet" are (a) no longer IC members (which may be indicative of the vast majority being not like them and considering it a career-ending move), and (b) very important for the ufologist cause to highlight as "former intelligence officers" to give their narrative an air of plausibility.
You won't see Knapp or Corbell at any UFO hearings sitting behind Bill the Contracted Plumber who claims to have seen shit at a USAF facility.
P.S. Oh well, as a plumber that's probably precisely what he's seen as I look back at my hasty fecal phraseology.
Right, though I wasn't so much suggesting that the ratio of UFO believers may be higher but rather proneness to conspiratorial thinking generally. Like you said, I don't think there's any evidence for that, but lack of evidence is sometimes due to lack of study in an area rather than studies failing to find evidence.
I'm obviously just speculating out loud here. Anjali's tweet made me wonder if the "circles" she's referring to happen to be the same ones Grusch was influenced by.
It's also just disconcerting to think people who work in the intelligence community might read a report from China saying they've found hostile NHIs on the dark side of the moon and believe said reports.
I suppose the explanation may simply be that you can be good at your assigned task but be terrible at others. Anjali herself has said her role while working for the intelligence community involved doing research on foreign leaders in an attempt to better understand and thereby influence them to further US interests.
Being good at that kind of task doesn't necessarily give you any kind of critical thinking skills to immunize you from believing obvious nonsense like NHIs on the moon, so just like the agencies themselves, our critical faculties themselves are compartmentalized and excellence in one ability doesn't always transfer to other domains.