"I'm not an economist but I've never heard of competition described as "negative-sum."" It is obvious that, if competition is strong for a cake with a given si

"I'm not an economist but I've never heard of competition described as "negative-sum."" It is obvious that, if competition is strong for a cake with a given size, that costs, e.g. for advertisement, may actually decrease the profits. While the size of the cake stays the same, the market players have less profits due to increased costs. So in the end everybody has a smaller slice. If I remember correctly, this has happened in a stagnant cigarette market where one player decided to increase his share. They spend a fortune on advertisement, as did the other since they don't want to lose their share. After some years the war stopped and everybody had more or less the same share as before, while having lost a tremendous amount of money on advertisement without gaining any benefit. This may also be a funny example: https://www.nytimes.com/2012/03/31/nyregion/in-manhattan-pizza-war-price-of-slice-keeps-dropping.html https://www.nytimes.com/2012/03/31/nyregion/in-manhattan-piz... "It's zero-sum because the consumer wins." A zero sum game has nothing to do with consumers in this example. It means, the cake has a given size. If you want to increase the size of your slice, you have to take something away from another player. A non-zero sum game would be were the cake (market) is growing. Every year you have a bigger cake. Then it is possible that you can increase your slice without reducing the slice of another player.