...and actually teaching in accredited institutions.
I have taught both at city college level and at college level (Art Center College of Design.) Also, I am listed at the Maine Photo Workshops as an instructor (although I have not taught any classes there yet.)
And it is true that you have to be paid for your efforts.
However, this does not always have to be in hard currency.
I do owe a lot and have found free Workshops a way to pay back in some small way what I received: About 12 years ago I received a kidney transplant from an unkown donor, a young man or woman, who died so I could live. Since that day I have tried to learn as much as possible about visual communication - and share freely what I know and understand. My total career in the visual arts and photography spans 42 years, incl. my apprenticeship and college education. My images have been published in most magazines and newspapers in the United States as well as in several European photo publications. In addition I have worked professionally with most camera types available (NOT incl. digital cameras - can't figure out how to get a useful image with these tools.) My "dayrate" while working commercially was not in the hundreds but in the thousands - and I was busy! - specializing in high end large format photography - primarily black and white.
By sharing this knowledge openly with those who ask gives me great satisfaction = one of the reasons I spend so much money and time doing these free workshops. I am not "learning as I go" = am way too old for that.