To be clear, the JFK Jr. conspiracy isn’t that he was dead and was resurrected, but that he faked his own death and assumed a new identity. Or even that he may have lost his memory and took on a new identity.
As for why the far right is going in on these loopy things? A lot of them are existing conspiracy theories that are being exploited. Part of this is just that Republicans (and Trump specifically) started pushing conspiracies when reality wasn’t working. Part of it is that the alt-right (i.e white supremacists) both believe conspiracies and prey on conspiracy theorists. Part of it is the cognitive dissonance with Trump being worse than people could conceive, and thus they wanted to believe that things aren’t as they seem. Part of it is that people turn to conspiracy theories as a way to cope with tragedy and uncertainty, like the pandemic (or, yes, JFK’s death or 9/11). Part of it is using deliberate religious language to dress it up for those who already believe that invisible powers like Satan are at work in the world.
Whatever the start, conspiracy theories tend to accumulate. Once you start believing “reality isn’t what they say it is” and have any restraints lifted, it’s just natural for them to come together. Part of this just happens, and part of this is stuff that con-men QAnon know they can exploit. The long-running conspiracy theories are already very good at spreading amongst fertile minds, having built up strong defenses.
It was not surprising at all to me that the JFKjr still be alive conspriacy got folded in like the rest. I’m sure that flat-earthism will show up.
As for “vaccines designed to kill you”? Sure, maybe some people were just saying it to troll the libs. But really that all started with the antimask stuff creating reluctance around the vaccine (as why do you need a vaccine if the virus wasn’t harmful enough to need to mask?) and the anti-vax groups who have existed forever taking advantage of that reluctance. People were looking for reasons to believe the vaccine was bad. Also, people who are scared will sometimes seek out reasons to justify their reluctance.
Then there’s also the way social media makes it all easier to spread, of course. The way their systems focus on engagement and usage time tends to encourage this, as does the focus on controversy. And then they were reluctant to do anything too much about it because true believers are more passionate and get more engagement, and they didn’t want to scare off anyone.
Yes, the stuff you’re hearing seems too absurd that people could believe it. And, to be fair, there’s no clear answer on how many people really believe any individual part. But these beliefs are real, and you’re seeing the natural combination of echo chamber effects and what happens when people start rejecting objective reality.
The believers are so deep that it doesn’t seem so absurd to them.