The thing that makes programming such a great thing is that you can do a bunch of it at once, then sit back and make a good living off the result with just a bit of maintenance.
That doesn't work with other candidates for "single greatest profession". Doctoring, lawyering, nailing things together, whatever. They don't scale the same way.
That is, there's no way for a Dentist to perform a single act of Dentistry that he can sell as a service on the Denternet and maintain his lifestyle indefinitely with just a few hours of work per week. He has to keep Dentisting day in, day out, either by hand or by running a practice, or the money stops rolling in.
Creative works such as music and writing have a similar scalability, but it can be more difficult to demonstrate value and it's nearly impossible to sell subscriptions to a single story or song.
He he, the kids never learn, even when the discussed article covers the crashes of this roller coaster job market... :-)
That said, an insightful comment.