Not many graphic designers out there?
That's extremely ignorant. There are many designers who are businessmen and women themselves who run their own agencies or businesses. Without them, you would not be able to promote or advertise your own business professionally.
I know many designers who have their own businesses with clientele they work with. Some work with in house teams at certain companies and some work independently on their own.
The creative industry is certainly not small. It's much bigger than you think it is. It's not just graphic designers or artists alone, but those in the video game and film production field as well. Even architects. Interior design. Industrial design. And so on.