Missed one of the big studies done recently: If you believe in one conspiracy theory, you're likely to believe in multiple, contradicting conspiracy theories.

Conspiracy theorists, then, are people who doubt for doubt's sake. There's a distrust in the official narrative and therefore, non-official narratives are given higher status simply for being non-official. Combine those two - a preference for the minority opinion and a snowball effect where doubts multiply - and you end up with a lunatic fringe pretty quickly. that is what we've all been acknowledging for centuries without really putting into words: if you doubt a few things, you're rational. If you doubt everything you're nuts.

Incidentally:

Elvis is alive. Princess Diana is alive, or the Queen killed her because she was pregnant and converting to Islam. Anna Chapman, CEO of PropertyFinder LLC, was a Russian spy. Fidel Castro shot JFK. The CIA hired mafia assassins to kill Fidel Castro. George Bush planned 9/11. The Jews planned 9/11. We all mass-hallucinated 9/11

1) Anna Chapman pled guilty to "spying lite."

2) Robert Wallace, former head of CIA OTS for decades (basically "Q"), describes - at great length - assassination methods and devices intended to be deployed against Castro in his book Spycraft. he also devotes a chapter on the ingenuity of a group of CIA operatives captured in Cuba for undisclosed reasons who spent several years in a Cuban prison and eventually led an uprising.

So yeah, there's some conspiracy theories. Then there's "conspiracy" theories. I mean, wikipedia. Mixing stuff revealed by the Church Committee in with "elvis is alive" kind of denigrates the subject.