It is much worse than that.
They are the end product of post-truth, and persistent political spin.
The Left has thier own versions, but are usually harmless, where the post truthers in the right tend to cause active harm.
Compare and contrast: "orgone pyramids and crystal healing in the age of aquarius" with "Baby eating reptilian overlords hungering for adenochrome!"
The rightwing version tends to proceed from a carefully cultivated narrative that "they are out to get you!", which is a propaganda tactic as old as mankind. This tends to manifest negative delusions, which result in further ideation, paranoia, and hypersensitivity to things outside the familiar or ordinary. Political groups averse to diversity, change, or curiosity favor instilling this state in thier supporters, and so such fraudulent messages are frequently broadcast.
The leftwing version tends to focus on an impossible, mystical level of inclusion, integration, or benevolence, with a strong belief that this is both real and attainable. The proponents of this view in politics tend to take the route of "religion is the opiate of the masses", and that "fat, happy people are easy to persuade, and control."
It is important to realize that this is a race to the bottom, in terms of compounding consequences. Both sides are not true monsters, bent on mindwashing. Rather, they perceive the ither as engaging in it, and then increase the degree of the propaganda messaging accordingly to try and reach a balance. This just motivates both sides to greater acts of divisive politick, and propaganda.
In short, it produces and sustains post-truth.
Critical evaluation, with a shared and empirically derived concept of a real physical world, is excluded by both propaganda approaches, as such would be resistant to the propaganda.
You do not need shadowy figures to have propaganda; just election campaign thinktanks.
In the case of rightwing propaganda, you have Heritage Group, Breitbart, Fox, and pals.
In the case of the Left Wing (which has moved away from the magic crystal hippy stuff and more and more toward neoliberalism as a pure belief) you have things like the clinton foundation, the DNC super PAC machinery, and more liberal press.
In both cases, the ribald denial of reality (No limits to growth! No reason to restrict trade or movement of people! World Govt is attainable, despite cultural and religious differences! / "THEY ARE OUT TO GET YOU, CONTROL YOUR THOUGHTS AND MAKE YOU A PART OF THE HIVE MIND!!! DOOOOOOOOOM!!") leads to systemically incorrect worldviews that are carefully selected for, and purposefully sustained.
Normal people end up in one of the end result populations, based on the media they consume.
They are not mentally ill. They are victims of post-truth.