Two of the best posts on success in writing I've read...

Two authors who have taken completely different routes to self-publishing success.

Daniel Arenson writes epic fantasy. Even with the popularity of Martin, epic fantasy is still a limited market. He’s made up with it by being extremely prolific—and very good, I’m sure (I haven’t read his work). http://www.kboards.com/index.php/topic,172709.0.html

Viola Revard writes erotica. She specifically chose a genre she knew was popular, and chose erotica because she knows it sells well. http://www.kboards.com/index.php/topic,182600.0.html

Both of these authors are successful. Both write for different reasons. Both are happy people pleased with their success.