Steve Sailer has a column up about conspiracy theories since the 1960s. I've been meaning to touch on this topic for awhile, so here goes, with a somewhat edited comment that I left.
One huge change from the '60s-'80s period to the 1993-and-after period is the victim of the conspiracy.
In the earlier period, it was a member of some powerful or influential establishment group, and they were targeted by other members of the powerful. Intra-elite factional violence. For example, in Three Days of the Condor, Robert Redford works for the CIA, and is being pursued by CIA agents. The initial conspiratorial bloodbath was also one group of CIA killing another. The JFK conspiracy theories had to do with an elite member killed by some other member or group within the elite. Ditto with Watergate. In Rambo II, there's a government conspiracy to cover up the fact that American soldiers were still being held prisoner in Vietnam (the POW / MIA belief). Admittedly the victims are not from the military elite, but it's still shown as a conspiracy within a single governmental organization, not affecting the average citizen.
In the period from 1993 and after, it's the average citizen who is a potential victim, and the agents are those he'd least suspect -- close friends, associates, or family, who will betray him when he lets them in close enough. In The Fugitive, the victim was an ordinary guy and his ordinary wife, and the initiator was one of his closest friends, who had ties to Big Pharma or something. Neo from The Matrix was an average guy, and so was that chick from The Net, both betrayed by those they'd trusted. Ordinary citizens were harmed by government cover-ups on The X-Files. The inner-city masses were the victims in conspiracy theories about the CIA selling crack in the ghetto to raise money for the Contras (a theory first promoted in 1996). And unlike JFK and Watergate, the 9/11 conspiracy theories all have to do with ordinary citizens as victims, no matter which elite group was supposedly responsible.
So, the message from the earlier narratives was that you shouldn't view the establishment as some benevolent, harmonious group -- just look what they do to their own people. You identified with the protagonist not because you were also a CIA member whose face could end up within the sights of a sniper rifle, but because he was a force of good and justice -- almost like a saint or angel, a higher-status creature than us in the audience, but who was going to try to keep the forces of evil up at the top from harming us on the ground.
In contrast, the message from the more recent narratives is that the establishment could be after you yourself, and they will probably try to get you through agents that you would normally find most trustworthy. Hence, you shouldn't let seemingly trustworthy people get close to you; and by transitivity, you shouldn't let anyone at all get close to you. You identified with the protagonist more out of personal fear -- it could be you, an ordinary citizen, who the higher powers might track down next, and it could be you who gets betrayed by your own friends and associates. Doesn't matter if you're not a doctor, computer programmer, etc. -- everybody works in some industry where the big wigs would want you disappeared if you stumbled onto inconvenient information.
The earlier narratives focus more on we the people not putting blind faith in the establishment, but rather reminding ourselves that there are power plays and factional violence within the elite themselves. They have no implications about how much an ordinary citizen should trust another ordinary citizen. The recent narratives focus on the average person isolating himself from the entire rest of society, perhaps excepting his closest blood relatives. They're part of the more general trend toward cocooning away from your fellow neighbor during the past 20 years.
We see the anti-establishment kinds of conspiracy theories during rising-crime times because people can see with their own eyes that the elites are not as omniscient, omnipotent, and omnibenevolent as they were thought to be. They get a pass on these matters during falling-crime times because, hey, whatever they're doing seems to be holding the violence level down. Only when it starts rising do we wake up to how clueless, impotent, and corrupt they can be -- why else does murder and rape become ever more frequent, year after year?
During falling-crime times, people don't feel as strong of a need to band together for common defense and support. But they need a pretext for splitting themselves apart from others. Now the focus of conspiracy theories is on how those you've trusted are actually going to betray you to the higher powers, who are almost ignored -- more disgust is heaped on your friends who'll betray you. How could they, after you let them in close? That'll teach you to trust other people. Now you've got a plausible, reassuring reason for why you have to unplug from community life and associate only with your nuclear family.