$500 isn't exactly much, given how long art takes to produce, how relatively infrequently that art will be bought, and how many extra expenses a "self-employed" artist has. I expect that most people selling art for $500 are hobbyists with some other means of financial support, because they're not going to earn enough to live on by selling art. Portraying them as corporate sellouts is just silly.
(The exception might be some digital artists working on commission. But they're probably drawing furry porn rather than something you might see in a gallery.)