As a former accountant, I get really annoyed when people use terms like “profit” and “ROI” incorrectly, especially in their marketing material. As I research different methods to market my books, I have been bombarded with emails to join courses. This is all well and good, I signed up to learn more about these courses, but lately, one of the course providers made the claim that I would only have to sell 20 books at $10 each to recover the cost of the course.