As a teen, Max had a great business mowing lawns. He used his hand-pushed power mower to build up a large clientele in a radius of his family’s house. When his friend and neighbor Charlie entered the business, ending Max’s local monopoly, Max didn’t have to cut his price—Charlie just expanded the radius of the client area.
Max knew he had problems, however, when he saw Charlie drive out of his garage on a riding mower. Charlie could now do four times as many lawns/day as Max. Max started losing customers when Charlie cut prices, as he could afford to (because his average cost/lawn was lower than Max’s, and had a minimum with a higher output.) Not wanting to compete on price, and unable to get his parents to buy a riding mower, Max decided his opportunity cost was above his now lower lawn-mowing wage, and he quit the business to open a lemonade stand.
(HT to MF)