His friend, Richard, was telling him that he doesn't care what his customers or the market thinks. Period. He ignores the market and customers and believes he's doing work only for himself. Seth Godin doesn't really mention who is this Richard person is or what kind of art he does, but as an art student and someone who would give anything to become a successful artist in the future, this Richard seems a bit too egotistical for art world, unless he's doing fine art for a living. I've always believed that you have to respect both the market and the customers who will buy your artwork or finances your projects and, in turn, help you to continue to produce and afford to produce your work. Very few forms of professional-level art are completely self-sufficeint.
Seth Godin says on end of his article, "If you're strong enough to do that, more power to you. If you do your art and the market rejects you, though, you need to make a choice. If your art has no market, it's still art. It just might not be a living."
To me, Richard must be the lonelist and luckist artist ever. Why so lucky? He does not have to worry about criticism of his work and the success or failure of his art.