Being an artist is easy; you just go around expressing yourself however you want.
And if that means that you yodel loudly while skipping through public parks, then go get 'em. Things get a lot harder if you want people to like your self-expression so much that they value it. What's value? I'm glad you asked.
Value is the willingness of others to give up something in exchange for what you offer them. Often that 'something' is money, because most everybody wants that. But there are plenty of other things people might find valuable too.
A lot of artists desire publicity, and would be happy to receive that in exchange for their work. I have a strange affection for socks, and have gladly given up a CD for a good pair or two. Even something as basic as respect is valuable for artists (and is often what we truly want anyway).
The point is that there are all sorts of ways to receive value, and whatever those are can help define what you see as artistic success. The important thing is that while we produce our art, we also communicate its worth to our audience. That's the key to turning a creative outlet into a fulfilling service to your community.