Jan Koum, the founder of WhatsApp, was born in a small village near Kiev in Ukraine. Coming from poverty, Koum's family emigrated to California, and Koum started learning about computers in his spare time. By the time he was 18, he had developed impressive skills, and in 1997, he was hired by Yahoo! as an infrastructure engineer.
He spent a decade in that industry before realizing the huge potential of the app industry in 2009 and starting WhatsApp Inc. By 2014, WhatsApp had become enormously popular. Facebook bought the app for a staggering $19 billion.
In 2014, he entered the Forbes list of the 400 richest Americans at no 62, with an estimated net worth of $7.5 billion, the highest-ranked newcomer to the list that year. As of August 2020, his net worth was estimated at $10.0 billion.