The Tech Whiz Behind Vine and HQ Trivia Made Millions in His 20s. He Was Dead by 34.

Colin Kroll , a college dropout turned startup millionaire, drifted through his company’s holiday party at Gran Morsi, a cozy Italian restaurant in downtown Manhattan. Dressed in a gray sweater and jeans, he chatted up employees and their plus ones. When one of his engineers offered to get Mr. Kroll …