That's just greed. This is a simple definition, from Wiki that explains it pretty well-
"Capitalism is an economic system based on the private ownership of the means of production and their operation for profit. Characteristics central to capitalism include private property, capital accumulation, wage labor, voluntary exchange, a price system, and competitive markets. "
Competitive markets are best for all- greed is what drives one company to gobble up the competition and become, well, ATT, Amazon, etc.
When competition exists in a way that everyone is on friendly terms, business can be fun- there's usually enough for all, everyone can pick the brand they want but if more than one seller has brands, stock can be shifted when the manufacturer approves it (otherwise, it's called 'trans-shipping and it violates the dealer agreement) and if people at one place make up 'facts' about the products or competition, it was possible to stop it by making a phone call. I enjoyed that time in the business- when we had a big Pioneer Truckload sale, we sold so much that Pioneer didn't have enough to supply us for the back-orders, so they arranged for us to pick up what we needed from another dealer in Madison- this was the same place that used to come into Milwaukee to have a big sale and stir up the market, had four stores at the time and was doing hundreds of millions of dollars in annual business. When we arrived, the owner of that company came out to talk to us to find out who was selling so much Pioneer out of one small store. He even came out to our place when he was in town- ever hear of TV Lenny?