You're incorrect on this. by having exclusivity on a product,...

You're incorrect on this. by having exclusivity on a product, you'll have higher margins on said product. Also they can sales targets to get a bonus on the side.

Altech Computers (an disti for I.T parts) went under as soon the big players left. They have brands like razer and cosair under their belt. For a while cosair was keeping altech a float
http://www.arnnet.com.au/article/590214/altech-computers-goes-into-administration/

MSY computers purposely sell products under their cost price to move stock. By moving high amount of volume they get incentives from the manufacturer

P.S. There isn't one way to make money by selling a product.