Potholes
Traveling salesman, Ray Albert Kroc, started the McDonald's empire after buying the name and concept from the McDonald brothers in the 1950s, but turning a profit proved to be a challenge, despite the popularity of the hamburgers.

Although Kroc sold 200 franchises within five years, and the unit's were grossing $37 million annually, his share after business expenses and licensing fees to the McDonald's was so small he had to earn money for his living expenses by selling milkshake mixers to restaurants.

Kroc had entered into a contract with the McDonald's that severely restricted how much he could charge for the hamburger franchises. Kroc eventually took on a partner with money savvy who found a way to restructure the business despite the original agreement. However, Kroc spent millions of dollars to buy his way out of the agreement with the McDonalds.

Lesson: A bad contract and a lack of business skill can ruin even a solid business idea.

Boas, M & Chain, S. (1976). Big Mac: the Unauthorized Story of McDonald's. P. 24.