Saritha Rai, writing for Bloomberg: A teenage entrepreneur who became a millionaire by 20 before sharing a billion-dollar fortune at 36, Bhavin Turakhia isn't afraid to think big. Now he's putting $45 million of his own money into building a rival to Slack and other office messaging platforms. Flock, a cloud-based team collaboration service, has attracted 25,000 enterprise users and customers including Tim Hortons, Whirlpool and Princeton University. It's a market that has already drawn interest from global technology giants Facebook, Amazon.com and Microsoft. This time last year, few had heard of Bhavin and his younger brother Divyank. That changed when they sold their advertising technology company Media.net, with customers including Yahoo, CNN and the New York Times, to a Chinese consortium for $900 million. The all-cash deal catapulted the duo from mere millionaires into the ranks of the super-rich. "I want to make Flock bigger and better than anything I've built before," Bhavin Turakhia, wearing his signature dark Levi's T-shirt and Puma sweatpants, said at his Bangalore offices.