I was talking to a (print) design friend the other day who's trying to learn to code. It's interesting to explain to a non-programmer what kind of person will/can become a programmer. If you don't love solving problems by digging and automating, then you will never be a programmer. As you say, not because of intelligence but rather desire and enjoyment.
Did your friend have any incentive to try it for themselves? For example, automating Photoshop using ActionScript? Maybe pro programmers like solving general problems, but professionals in other fields would be interested in solving things in just their domain.
Great idea. I'll mention that. He was coming at it from a somewhat arbitrary expanding-skillset approach, wanting to get his feet wet on the web side of things. I was explaining to him the difference between a creation that "looks" a certain way vs a creation that that "does" something.
