I read Eric Hoffer’s The True Believer: Thoughts on the Nature of Mass Movements a very long time ago. I believe I heard my father mention it when I was very young and it got my attention. If you want to know how mass movements arise, or more correctly, are constructed, read this. Saw a blog post in my news feed discussing Hoffer and his True Believers. A good overview, but I still recommend the book.

True Believers