Well, that is sometimes true. However, there are other reasons why people write courses. Take me for instance, I did it to fund my account. Although sales are not what my marketing guy promised me, so it's a mute point anyway.
If I had 150K (which is really nothing), I would be done. My regular performance, times as many contracts as 50K can controll each time is more than enough to support me. So, by hook, or by crook, my goal is to get 150K as fast as i can. I am even thinking of going to a brokerage house for a couple of years if I have to.
Although, I have to say, my approach is pretty different than most guys hocking stuff. Over time, i have pretty much given my system away here. Maybe thats why I can't sell anything....