Pyramid scheme, not profit scheme.
Pyramid because the shape is a pyramid.
The first person, the one who sent out the original picture, received X books and sent none.
The next layer sent one book, and possibly received up to 36.
But those 36 each need 36 new people. It’s impossible. You’d hit the population of the earth in just a few rounds.
Right, it’s just a front door lol. I never considered that was a thing.