What does programming in my spare time have to do with studying for my job? I think the idea that the article was trying to convey was that the best programmers love the work enough that they'd be doing it on their own, even if they weren't paid for it.

I work an 8 hour day. I may spend another several hours coding on some days, but I would characterize that as play, not work. I try to do things that I don't think I could convince anyone to pay me for.