And that's why the cycle continues.
I think if a design is unique, more useful and better, people will pay more. But if it's like everyone else, they could consider it common and pay less. It should be rare and irresistible... that will create high demand and the amount they pay will be enough. Competition should encourage creators to improve on their works and be different.
And sadly, they keep on doing that because there are other designers that do take such task because they are in need.