Two Points, Sir

One, adherence to 'conspiracy theories' tracks well with a a sense of powerlessness, both personal and political. The first element of the thing is not too dangerous, as persons who perceive themselves as powerless personally generally are, while the second, if widespread enough in a polity, can prove dangerous indeed, as feeling unable to effect the actions of one's government or functions of one's society can lead to apathetic withdrawl, or angry and violent engagement, often without much clear sense of what actually is wrong, or how it can be fixed.

Second, adherence to 'conspiracy theories' provides two particular spiritual balms. Such theories provide a sense of certainty and understanding, both hard to come by in this modern world, and such theories provide a sense of being on the 'inside', of knowing more and understanding more, in short, a sense of being superior, to the mass of other people who just cannot see, and do not 'get it'. These feelings are very comforting, and especially so for people who actually do feel powerless and isolated and left behind.