Musicians don't retire; they stop when there's no more music in them.
I think this goes true for writers, too. It's just something that's in the heart of every artist ... this need to let your feelings out in a certain medium (writing, music, photography ... ). I believe that true artists are really good at what they do, and don't really care much if they earn from it, or not.
It's just something that they do. and they do it real well.