Benjamin "Kickz" Kapelushnik started selling sneakers to friends in fourth grade. Now, at 18, he runs Sneaker Don, and (as his signature catchphrase puts it) business is boomin'. How does a hobby become a sneaker empire? "I just felt like I had the sauce, so I just started buying shoes," he told Business Insider. Fans include DJ Khaled, Sean "P. Diddy" Combs and Odell Beckham Jr.