Also anecdotal, but the best self-taught programmers I know (or knew, at this point) came from the demoscene and often made their careers in game development.

The people you mention made a common mistake. They went to a university to study X, and not because they were interested in X but because they wanted to do Y and believed that X would be useful in it. That's a mistake, because academic education does not work like that. Mastering the curriculum does not make you an expert in the field. The curriculum is only a scaffold. You are always expected to learn more, both because you should find the topic interesting and because learning more makes sense.