From my experience, people choose to believe in propaganda out
of their own free will, just so to assuage their doubts, their
fantasies, and their pride.
Human nature really. Ultimately, many people don't know how to
think with their head, instead of their heart.
The worse part, is that people willingly believe a pack of lies
knowing that they are lies. Either they are simply not being honest
with themselves, or they think things in black and white.