My understanding is that they come straight from Lifespring, an old cult of which David Gilcrease was a part of. I recall something along the lines of Lifespring being inspired as a get-rich-quick scheme by someone with a lackluster education after failing with some lame scam, but don't quote me on that.
I assume they are based on POW camps and cults and their tactics, specifically most likely from descriptions, testimony of experience, and psychoanalysis books.