I have read some weird books, and this is one of the crown jewels in the odd collection. I read it a long time ago, so I'll write a few thoughts on the conspiratorial mindset instead.
Conspiracy theorists need a few conditions to exist: they have to be isolated from the halls of power, live in a society where PR blandishments are the primary mode of communication from the corporate world to the general public, lack a unified vision of normal society and be exposed to social dysfunction. Thus, the people they tend to attract are at the bottom of the socioeconomic ladder; though their ideas are utterly wrong and often ridiculous, scorn is not the appropriate response.
I'm sure conspiracy theorists have always existed, but it seems to me that perspectives like this book are distinctly modern. It is a feature of modernity that there is no order to the world; utility is the only ordering principle, which turns out to be highly subjective one in an individualistic society. As a result, academic disciplines are fragmented; modernity has no way to connect physics and art. When taken with the fact that we live in a highly complex, pluralistic society, it is no mystery that some people find it difficult to see how our society is ordered. This is especially true for people who lack community, and whose experience of home is that broken families are normal. To these people, society lacks coherence, and yet they cannot turn off that part of them which insists there is meaning to the events that occur. Perhaps too, because they cannot see order in the ordinary things of life, and yet are so desperate to find meaning, their faculty for seeing patterns channeled exclusively into areas in which they have little direct experience, and thus appears overactive.
Yet, there are many people who experience disorder in their lives, but choose to believe the explanations of politicians (though perhaps with some cynicism), and just accept that the world is a tragic place. Thus, an essential part of a conspiracy theorist's mindset is that they must also believe that they are being lied to - it's no mistake that paranoia is highly associated with conspiracy theory belief. Social dysfunction probably contributes to this problem, by reducing trust, especially in those that were supposed to be nearest to you. I think there are at least two additional components, however. One is that the way corporate and political culture communicates is often self-evidently PR friendly, and will sometimes keep things 'in the family' (that is, until their adversaries extract it from them). The second is that media technology, especially television, is viewed cynically, as a means to manipulate the public. Or, as George Orwell put it, all art is propaganda. Unlike other modes of artistic expression, however, everyone acts on camera; to the paranoid mind, everything on screen can be read as an illusion.
The one instinct I think they have correct is that there is a larger meaning to historical events. Ordinary people may see this in terms of battling ideologies, or the heroism of man in a tragic world, or as a religious struggle to reach God. In a materialist, secular society the powers that be cannot be located in the spiritual world. In the medieval ages, it was still possible to attribute events to the creatures of folklore, or to the devil. Instead, in our world, it must be real people who have done real things (though conspiracy theories often refer to the occult). Thus, because everything that is plain is a lie, we have elaborate explanations for how the Illuminati and Co. run the world. Everyone has a story of why the world is the way it is; conspiracy theories are among the less credible versions.
It seems the scene has shifted since this book was published. Research (talk about a word with a double meaning here!) indicates that some conspiracy theories have become mainstream in American culture - they are no longer fringe beliefs. This seems partly due to new media, which has little means of controlling what gets shared. But perhaps this also spells the end for such conspiracy theories, because they require that only a minority can know the truth. As the proverb goes, if everyone believes it, is it still a conspiracy?