Two business school professors unpack what brands get wrong when they try to expand their customer base and how to avoid their mistakes. There is a type of business story that has become nearly cliché: A legacy brand is facing stagnating growth. Loyal customers are aging out, and new customers aren’t taking their place. So the brand reinvents itself to pull in a younger segment of the market, often by borrowing ideas from cooler competitors to seem more “on-trend.”