I believe the drive to believe in actual conspiracy theories, and a belief that somehow there is a secret organization or mastermind pulling all the strings, comes from a religious impulse people have. People don't want to think they live in an unsafe and irrational world that kills for nor reason, and makes the concept of doing right being rewarded a mockery. So, if they don't look to God, they end up believing somehow there are men who form cabals who can pull everything off. The belief is that, if this is so, then somehow maybe you can bargain and reason with such individuals for mercy. Or, if not bargain, fight them and end up taking control of their seat of power for yourself. In this, I won't deny that men do attempt this and do attempt to conspire. However, what I do is look to the metaphors in the TV show X-Files to explain it. You do have the conspiracy battling the unknown (the X-Files cases) for control, but there is no guarantee they can control it.
Anyhow, that is my two cents. Also keep in mind, the brain is a pattern-forming machine, which enables it to place order in chaos to organize things so they have value. Because the mind does this, it is easy to start seeing patterns everywhere, if you look hard enough, and come to believe that the cabal is doing it. I am of the belief any cabal hides in the noise to do what it wants, rather than try to make the noise so. Normal cabals don't try to control the world, just have order in the piece they care about, so they prosper or aren't harmed.