i don't understand why people fall for it. if anyone is making a killing in their business, they're not going to sell a book about how to create a killing in th

i don't understand why people fall for it. if anyone is making a killing in their business, they're not going to sell a book about how to create a killing in thay field. (a) they don't need to because they're already making a killing (b) ahy create more competition for yourself/give away your secrets? if selling your secrets nets more money than the business... then obviously it wasn't a good business