I definitely understand your concerns. Here's some answers:
I'm doing this. My name is Colin McDonnell, my email is colinmcd94@gmail.com. I'm not a scammer.
The service definitely defies some expectations, since its entire goal is to induce a given behavior through (mostly) negative reinforcement. Clearly I (that is, "The Jerk") benefits if people drop the habit. That's part of the incentive. It's why the service is personified as a Jerk...you're not supposed to like him and you certainly don't want him to have your money.
Also remember, there's a positive reinforcement too, in the form of the end-of-year book. And $29 is a GREAT price for a custom hardbound book with shipping. Here's a comparable service that charges $79: https://www.storyworth.com/holidays. We expect to make the vast majority of profit from the cheat day markup.