I just started reading xkcd Volume 0, because it was added to the Humble eBook Bundle (which is now closed), and came across a phrase that resonated with me. Apparently, writes Munroe in the introduction, Terry Pratchett quit his day job when he realised that every day he went to work was causing him to lose money because his writing "hobby" had become so lucrative. He called it "the Pratchett Point".
I like that idea for creative work. Keep a day job where possible, but keep at your artistic work too. Make money from it (I'm still working on that part). At some point, if you're destined to become a success, your day job and your creative work will swap places and suddenly you'd be better off being a full-time artist. One day, if I am very lucky, my writing or acting or impromptu office supply sculpting will become my primary source of income and I'd be better off quitting software to focus on that full-time. If that point never comes (and I have yet to make a single cent from my writing or acting) then I will keep making software and there's no real harm done except to my pride.
Mokalus of Borg
PS - Most artists would never hit their Pratchett point.
PPS - But as long as they produce good work and enjoy it, does that matter?