When I was gigging around Nashville, a friend used to take me in to sessions at the studios. The GOOD living that the session musicians made was not from the established artists but from the thousands of out of town folks who paid through the nose to have a "hit Nashville sound" record made. I've never heard of anyone who answered one of those "we want your songs" or "we want your poems" or "wanna make an album?" ads in the back of magazines becoming successful that way.
I Think Fortunato hit the nail on the head.
Rick