David McCandless put together this graphic showing what it takes, in terms of CD sales and audio streams, to make a minimum wage with music. The takeaway: It's hard.
Even with the relatively healthy profits from CDs (a fast-fading format), a musician has to sell hundreds, month after month, to make a living. I think it's just a reality there are more people who want to be musicians than the market can support, even (especially?) in the digital age. That doesn't mean aspiring Jack Johnsons or Thom Yorkes can't make music. It's just that lots of them are going to have to do it for love, not money.