It's much easier to believe that others are responsible for your situation in life than to take responsibility for it yourself. This is especially pronounced among people who believe conspiracy theories.
How about just bored?
Life may just be too boring for them, so they create excitement through elaborate conspiracies that they, themselves, can participate in. Some are mentally unstable. Some are just easily confused. I think the reason for each is specific to the individual's situation.
I imagine in the grand pantheon of political intrigue there has been at least one conspiracy theory that was true - but whatever that theory was, it must be very lonely there. Conspiracy theories are the currency of the weak-minded - typically bandied about by those that wear velcro-shoes.
I imagine in the grand pantheon of political intrigue there has been at least one hyper-partisan hack that was right -- but whoever it was, they must've been lonely. Hyper-partisanship is the currency of the weak-minded, typically bandied about by those that wear secretly wear tightie-whities with network and party logos printed on them.
A conspiracy theorist's attempts to project it's fiction onto real-life people, groups and organizations. It purports to actually be true that which really is fiction and this is the problem. Their attempt to project into reality that which at best is fiction is one reason I believe they have a mental illness.
One person who is a conspiracy theorist says he gives an "accurate account of history." The problem is that in his paranoid imagination he believes he is right. Again, it does not matter if you show him to be totally wrong, because to him you then become part of the conspiracy. In short they have lost all touch with reality.
He and other conspiracy theorists change their so called evidence in response to each part of the conspiracy that is debunked. As soon as one delusion is unmasked, they simply invent another to replace it, and deny the first ever exsisted. Theorists aften argue that those who debunk such information are themselves involved in the conspiracy.
If some new information appears to undermine a conspiracy theory, either the plot is changed to make it consistent with the new information, or the theorist questions the legitimacy of the new information. This is something one can see over and over again in their comments.
They spend countless hours looking for things to support their theory. The sad thing is that when they find information that shows them wrong they simply bypass it and find people [and sources] to support their theory. They have the Idea that the greater the lie the more easily it is swallowed by the likeminded people.