Yes, undoubtedly. It's better than sex (almost). And unlike Treewind, for me money doesn't come into it (been a semi-pro for 40 years, much more so in the first 20 but still get a bit of paid work) - the rush is no stronger when my palm's greased than when I just do it for pleasure.

It's the same thing as saying "Why do people sky-dive?" or "Are you a crochet-junkie?". We do what we do because we can, and because we love doing it - if we didn't it would just be a day at the office.
S:0)