True paranoia-- in the clinical sense-- can be quite disheartening to witness. My empathy goes out to these people, who cannot manage to function without intense feelings of persecution and worse.
Sadly? There are other cases, who are not suffering a brain malfunction (as above) but instead, have been grossly manipulated by circumstances, and are operating under absolutely false pretenses. Fortunately? If they have the will, they can easily get better by the simple act of Studying Things. Knowledge is the cure for what ails them, and in this day of Al Gore's Intertubes? Knowledge is practically free-- but there is a danger.
The interwebs also contain the largest collection of human-created bull exhaust ever compiled, since the beginning of time.
One thing I have observed among the younger sort, who grew up with this Monster? They are, usually, a lot better at filtering out what is plainly dumb, and what is useful. Some of us old Fogies, who grew up with Dead Tree Encyclopedias (a kind of primitive internet), which required physical travel to something called a Library, to access Knowledge. Back then? The creation of an Encyclopedia was so expensive, that -- usually-- the knowledge contained therein was pretty high quality. It therefore took more work for us post-WW2 kids to develop a really good BS detector.
Alas... some of our generation never did learn that trick...