You see how easy it is to learn marketing, pick up a few books and learn.
To learn how to shoot with a camera is pretty easy. To learn how to shoot good porn and get the best out of a model is tough.
Which is why being a good marketing man is such a flooded profession and pays poorly. Whereas being a good porn shooter is a lot less crowded and pays better.
Damian could read all the books on porn and shooting there has ever been printed. But he would be bankrupt long before he had a clue how to work a model. And that goes for many other people.
So it's back to the old supply and demand rule. If it's abundant, the ROI is low. If it's rare the ROI is high, for the same amount of sweat and toil.