Here is an indirect answer/opinion... I think it initially boils down to the fact that many conspiracy theorists are just like regular sheeple. The
'Believers' usually fall into one of two groups from what I can tell. A) They lack and require some kind of rigid belief system, and so they adopt one
that is convenient. B) They do not actually believe, but have become mesmerized in a similar way that a sports fan obsesses over their home team.
Essentially it has become entertainment.
Of course I am generalizing, it may not always be that black/white and I assume there are critical thinkers out there that are researching it.
To give the believers a boost... I did read an article not too long ago where an astronomer was able to explain several gravitational anomolies in
outter solar system by the additon of a planet into an elongated orbit. According to his calculations the planet would never have any significant
gravitational effect on our inner solar system, and would barely be visible on most telescopes at its closest distance from earth. He believes it was
knocked out of orbit from a neighboring solar system and is responsible for asteroids/comets being pulled out of the oort cloud. I can't remember the
exact name but it gave the impression he did have some level of credibility in the scientific community. He makes no reference to Nibiru, PlanetX, or
Nemesis....
edit on 25-7-2012 by centrifugal because: (no reason given)