Believe it or not, teaching IS doing. It is a separate skill set, a separate collection of values, and a separate set interests.
The idea that all who choose to be professors are failures at business is totally juvenile. What's more, it's arrogant in the extreme to think that those who are successful in business would automatically make good professors, and it's even worse to think that someone who happened to have both skill sets would find no reason to teach once they were rich.
Edit: Of course, this is addressed to PG, not to the poster of the summary.
I used to subscribe to your point-of-view, but don't anymore.
The traditional teacher-pupil relationship is well over-rated, and may be more efficient in the very start of the learning curve. Once the basic toolset is available, I'd much rather transition to deliberate solo practice and a mentor-mentee/craftsman-apprentice relationship.
In my experience, during any kind of medical/surgical training, these "wet-fingered" surgeons/mentors are the really ones that are sought for, not the big names who are famous on lectures halls and congresses. I believe this is also true for other complex skills as well, such as in startups. YMMV though.