By the time Joe Gebbia Jr. reached his senior year at Brookwood High School in Gwinnett County, he was already becoming a successful entrepreneur.

Gebbia, a devoted art student, was disappointed in the school’s senior T-shirts for the class of 2000, so he redesigned them and sold his own.

“People loved it,” recalled Gebbia, now 40, a co-founder of Airbnb. “It was a big hit.”