The problem with complex systems is that once they reach an enormous size, there are practically an infinite amount of actions that occur within that system. These actions can be as big as going to war and minute as the president's secretary taking a breath. But since there are so many different actions going on, you can pull say any 10 of those unrelated actions and give birth to a conspiracy.
Funny thing is that that conspiracy will one day reach an enormouns size and then feed itself. Throw in a couple extremists and away you go.
I'm not saying that something may have happened or something else didn't happen. But come on, I heard enough theories about who shot JFK and why. Even once, someone said that my grandmother was the mastermind behind it because she didn't like the situation with Marilyn Monroe.
But I think my favorite one was that JFK was killed by people from the future. Some guys in the distance future invented time travel but the government of that time wouldn't let them patent it, make money off of it, etc. So these inventors went back in time to make their great, great, great grandparents super rich so they would eventually inherit the family nest egg. The grandparents were working privately for the military and were going to sell the rights to the government. This angered the guys from the future and they ended up killing JFK just to keep everyone else in line.
The funny thing about it was that the guys from the future already knew that Kennedy was going to get shot. They just took credit for it. Ok, so who really shot Kennedy? Great theory.
And then throw in stuff like this: