Delusions are thankfully a well researched and understood topic. It has been well studies by psychology, psychiatry and political studies. Until the 90s, it was presumed to be related to paranoid traits or lower IQ, but that idea was proven wrong. Since then, it has been considered a mechanism for regulating self esteem, and I agree with this official position.
When someone has problems with self esteem, he can solve the problem in a couple of ways. He can fall into conspiracy theories about politics or any other topic. Suddently his importance in the world went from zero to the top. He’s now part of an elite group of smart/enlightened/spiritually advanced/etc. people. The second option is to become a religious extremist. Due to his new radical, unusual, non-mainstream views, he is now part of a small group of people who got it right. A third option is that of the “crackpot scicentist”. Google “crackpot index”. A scientist with low self esteem might fall in love with one of his theories. It provides a ton of narcissistic supply to the person.
All people can fall into conspiracy theories due to the beginner effect, or the “drugger-krugger” effect. If somebody is a noob in a field, he is way more likely to fall into stupid theories. That’s one of the reasons why people tend to develop such theories about politics. Few have real experience in politics, most are beginners but fall to see that their level of competence in the field is much lower than they think.
In order to really fall deep into conspiracy theories, one has to be in a period in life where his self esteem is super low. In my opinion this also explains the age distribution of schizo. It’s difficult to get into such a situation if one has been an engineer/doctor/etc. for 20 years. Even if his whole family dies, that will only lead him into depression, not into problems with self-esteem. But, if somebody just took and failed his medicine exam, he might start believing he is not good enough for the job, he might start being unsure about himself, he might start contemplating that he will only be good for a much lower job, etc. If you add some social pressure on top of this from his parents of friends, the situation will be even worse.
It is this kind of situations that make people prone to conspiracy theories, according to research. Now, imagine the person start to take more and more narcissistic supply from his theories, since it’s the only thing he has. Imagine he starts thinking about it 1 hour/day or worse, he starts fantasising and day-dreaming about him getting a ton of recognition from the world due to being so smart and figuring it out.
The path from this into psychosis is easy. At one point, the conspiracy turns global, turns super important. If someone for example believes he has discovered something important in the field of mental health, he will feel pressured to spread it to the world, to participate in conferences, etc. This is normal. But now imagine that the person goes even further and thinks about his theory non stop for 2 weeks, feeling more and more pressure, feeling that it’s a super important and urgent thing. It is this state of high importance/dopamine that is called psychosis.
When dopamine is at very high levels, every though looks more important, as can be seen through the effects of weed/amphetamine/legal canabiloids and other drugs that increase your dopamine levels. If someone reads an article while stoned, that article will seem much more important and much more convincing than it would do sober. Whatever thought that comes to his mind looks much more important.
The phenomenon of Jerusalim or Paris tourist psychosis looks similar and all cases are identical. Somebody religious plans his trip to Jerusalism for months or even years, thinking it will be a highly important thing for him. After ariving there with dopamine levels being through the roof, he is shocked to find that it’s a normal city like any other, with bad traffic and mcdonalds. At evening, he dresses in the hotel sheet, goes in front of the hotel and starts preaching about how everyone should return to a more simple way of living. All cases are identical, all follow this scenario because those are the first thoughts that come to ones mind after such an experience and that’s where the dopamine gets put.