it's really easy to dump $10k into framebuilding before you make any money, even if you have experience. Insurance is over $2k a year, for one thing. The thing you have to recognize is that you might not make any money anyway. There are a number of builders who have sought other opportunities in the last couple of years. It's like any other business -- most fail. There really aren't very many full-time builders around.
Of course, I don't know if I really have any standing here, Trek sold my 4th frame