I've had discussion with a guy in lab of a top university and they believed 911 was an inside job. steel beams and all that.
It doesn't seem to correlate to technical ability, there are something in psychology that draws a certain type of people towards conspiracy and in which they go into a mental state where normal explanations are removed from their logic and they go seek outlandish explanations or slightly hard to explain things and turn a twist into it. I don't understand why but I think a pretty decent amount of people subscribe to this kind of thinking.
Neurology researchers here, please give us answers.