Onur Cobanli explains:
When you sell a design you are also selling your name, in two ways; firstly by selling a design, getting it produced will also help spread news about your name, make you famous, and perhaps sell more designs in future, on the other hand, when you sell a design you sell your name, many clients want to buy a name, so famous designers tend to sell more just because the clients, manufacturers, producers wishes to use the name more than the product.