I attribute it to the fact that the world is so complex and convoluted and just downright ugly that some of us try to arrange it in a simple, clean way. Government is evil, people are good. Most people are sheep, we are enlightened. To say otherwise would be to admit that we barely understand 10% of what's going on, or worse, that we have no control over it. Now, if we figured out the Illuminati's game? Then we're in control and we understand.
That, and our endless obsession with finding patterns in randomness. It'll be the death of us.