A lot of em get real jobs. Frequently in the music industry, where there are many ways to make a living other than in Unitarian Church basement clubs.

J Ian for example is a songwriter etc. in Nashville. And she is a HELL of a performer, and since she had a whole string of hits in her first career as an angst-ridden teenage singer-songwriter, I don't think she really fits your question.

There isn't just one answer, of course, but people that have found out how the music biz works have lots of options.

W-O