I've had my online shop for ten years. For the first three years, I kept working at my day job, freelance ghostwriting, and poured the money into the shop, which is centered around my personal interests. It was great to finally quit the ghostwriting. I was getting burned out. However, I have never made as much as I did when I was ghostwriting, and I work many more hours. I have no benefits or retirement and haven't had a vacation in years. It is a constant struggle to keep up with new developments on the web. I work alone at home, and I have often wondered how someone who was part of team for years could adjust to ordering tasks oneself and always being the sole person responsible for every decision. That said, I feel very lucky that I have not had to get a regular job, esp. in this economy.
My best advice: find a niche you can call your own, diversify your income stream, keep good books, and pay your taxes.