In an interview with the BBC, Mick Jagger is asked about things like file sharing, and he notes that, realistically, artists only made money selling music directly for a very short time:
But I have a take on that – people only made money out of records for a very, very small time. When The Rolling Stones started out, we didn't make any money out of records because record companies wouldn't pay you! They didn't pay anyone!
Then, there was a small period from 1970 to 1997, where people did get paid, and they got paid very handsomely and everyone made money. But now that period has gone.
So if you look at the history of recorded music from 1900 to now, there was a 25 year period where artists did very well, but the rest of the time they didn't.