I have ideas about what it is that makes people want to believe nonsense, but I guess what bugs me most is the laziness of the whole thing. Have questions? There are answers all over the place from people who actually know what they're talking about. Don't like the answers? Make a fucking phone call. Can you verify your kooky theory? If you can, by all means present it. But to spend X years going "something doesn't add up" or "there are unanswered questions" means you don't know what you're talking about and you're uninterested in answers that don't suit you.
At this point "I dunno what hit the Pentagon" or "the towers were wired to explode" are flat-earth equivalents. I remain open to the possibility of being proven wrong, just as I am about space aliens pooping in your cornflakes or Aleister Crowley having bona-fide magickal powers that years later