90% of Americans believe at least one conspiracy theory

that doesn't explain the appeal of choosing to believe in something that 90%+ don't and will tell you that you're a moron for believing it

Sometimes the people who are shun by the 90%+ form groups.

Some time ago I saw a documentary about flat Earthers. One of the more common characteristics among them was that they were loners, shun by others, bullied in school... I am willing to bet, a number of them don't even believe the Earth is flat, but they just enjoy the camaraderie and being able to belong to a group that treats them like they matter.