my opinion is that a lot of the theories have just enough evidence to keep them going combined with random pieces of information that seem to fit a little bit of the theory.
this then causes fear which leads to a minor form of paranoia
an example of this was last year, i was doing a bit of research on 2012. When information fit then i kept it but when it didn't i would forget about
it, this created a lot of little bits of information. i soon began to get worried, before i knew it i was #ting myself about the end of the world.
later on i read a few threads that had different theories about 2012, not involving the end of the world.
people can get so worked up of conspiracies that they don't listen to reason. which causes an easily cure able form of paranoia