For some reason or another, while inebriated at a party, the topic came around to discussing a movie called Zeitgeist and other various assorted conspiracy theories. I have come up with a hypothesis of my own, although it isn't a conspiracy, it does relate to the people that formulate and believe in conspiracies.
My hypothesis is very simple, so I'll do my best to explain it as such.
Conspiracy theorists and believers of conspiracies always tend to accept a whole battalion of conspiracy theories. I have never met a person who thinks 9/11 was an inside job that doesn't also believe in multiple other conspiracies. Other common conspiracies that they tend to believe in are New World Order conspiracies, Illuminati, Moon Landing Hoax, World Bank conspiracies and even some conspiracies dating back hundreds of years. So with this in mind, I propose that perhaps some people are more prone to conspiratorial thinking than others. I'm not a neuroscience expert, but I suspect that it is a result of brain conditioning or that critical thinking skills aren't being applied consistently that causes some people to be more susceptible to believing grandiose conspiracies.
I hope that made sense...