It's much easier to make a book sound epic, insightful and/or wonderful than it is to actually write something like that. It might take a while for the user to give up, but who cares if people only get 50-100 pages into your book before quitting if you can attract multiple times more people?

> Additionally, I think you're first two points mostly address the outliers on the bell curve.

I have personally alternated between those extremes in the last six months. I've read multiple thousands of pages one month, and been too busy to read anything the next. I also suspect there's a population of people that will sign up and forget about it for long periods - just like gym memberships.