Are Amazon Seller Training Courses a Fraud?

Okay, here's one for you - why do so many Amazon sellers seem to be so active with blogging, YouTube and in creating and promoting educational courses? 

The ones which we revere to be the gurus, never seem to be down in the trenches. They supposedly know the secrets of making things work, but don't actually do that full-time. Rather, they gravitate towards consulting or educating others.

Simple logic dictates that if those people were so successful at selling on Amazon and generating the huge revenue that they proclaim, they wouldn't give a damn about creating YouTube videos or training courses. Unless of course, they have some noble cause to help others out, which I doubt is on the top of their priority lists.

So why are these people spending their time creating YouTube videos and courses if they were so successful at what they teach? To me, it looks like there is higher potential for generating income from telling people the secrets about making money, than actually doing it for yourself.

There is a guy I follow on YouTube, named Tanner Fox. His YouTube channel is full of shouty videos which tell you how easy it is to get started with Amazon and how much cash you can make. He claims that he has earned so much that he was able to afford a Lamborghini after a year of doing that.

He also happens to have a course, which tells you all the secrets which will get you that Lambo in no time. The course costs $500 bucks, but that's a negligible investment for a Lambo, right?

No one can say for certain what the value of any particular piece of information is (its really subjective), but in my opinion, what is in these courses can be found freely on the web, you just need to search for it. 

People are so naive, that they pay huge money for these courses and come out of them less prepared, than anyone who has taken genuine interest in the idea and has been obsessed with finding the answers for themselves. 

I think there is so much out there on the web, that it doesn't make sense to pay so much for coaching, especially if it is in the form of a course. Individual consultation with an expert is a whole different thing and you can actually get couched, whereas courses are built to just generate passive income for their authors.

What do you think, can YouTubers be trusted?