An interview with one of the more successful and marketable fine art photographers today (at least in the US and Japan)
A great quote from that interview:
"My expenses are almost as high as my photography income and I have so little left at the end even when I am lucky. So, maybe I am not qualified to answer this question. Then why am I doing photography? I think it is a combination of passion and stupidity. For me, photography is intellectual, ...artistic, and curiosity fulfilling. I love making photographs."