It's extremely hard to make a living as an artist. My SIL's husband (also a very talented portraitist) was a grahic artist for a number of years until he got totally burnt out; I don't think he's picked up a brush in ten years now. I know one fantasy artist that was finally, after about 15 years, able to make the jump to doing book covers, cards and the like, and I know others that have quit who if they're still painting are just doing it for their own enjoyment. It's not quite as bad as making it in Hollywood, but it's difficult.
It takes a while until you're able to "give up the day job!"