5000 Fans
An artist who has 5000 hardcore fans to give him or her $20 each year (for their music, art, etc) stands to make $100K per year.
or: 100,000 fans @ $1 (digital download) or 1,000,000 fans @ 10 cents (micropayment)!
Sure, there might be overhead costs in the production of said music/art, but even if this overhead was an outrageous %50 of the profit, you’d still be making $50K per year.