Who are the most successful self-taught tech founders? originally appeared on Quora - the knowledge sharing network where compelling questions are answered by people with unique insights

Jan Koum is the founder of WhatsApp, which he sold to Facebook for $22 billion in 2014. He taught himself to code using a bunch of used books, and overcame enormous personal odds before he ever started WhatsApp. His story, which began on the outskirts of Kiev, Ukraine, is a truly rags-to-riches tale.

When Jan was growing up in Ukraine, his home had no hot water and little connection to the outside world. It did have a telephone, but his mother was afraid to use it because their family was Jewish, and Ukraine's secret police had a long history of antisemitic actions toward the Jewish population.

In 1992, Jan immigrated with his mother and grandmother to Mountain View, California. He was 16 at the time, and the family stayed in a government-sponsored two-bedroom apartment. Today, Mountain View is a booming tech center, but in those days housing was still low-cost and somewhat abundant.

To put together enough money to survive, Jan's mother babysat and Jan swept supermarket floors. It was a hard life in a new country, but things would get even more difficult from there.

Jan's father, who was planning to join the family, fell ill before he could make the trip. He eventually died in 1997. Then Jan's mother was diagnosed with cancer (to which she would eventually succumb in 2000). The family was forced to rely on food stamps just to survive.

Few people could fault Jan if his life began to unravel at this point. Immigrating to a new culture and country is hard enough, but when you lose both of your parents in the span of five years, and you lift your head up and notice a world around you that doesn't add up, that's an inconceivable kind of pain.

But Jan took the lumps as they came. When he was still in high school, he began to buy books from a used book store, and to teach himself networking engineering. When he finished with the books, he'd return them and get his money back. He used his self-taught skills to land himself a job at Ernst & Young while still in university.

One of his first clients was the then-fledgling Yahoo. After spending only a short time with Jan, their team was so impressed by him that they too offered him a job. Before he knew it, he was working with, among other Yahoo stars, Brian Acton, one of Yahoo's earliest employees.

Brian's earliest recollections of Jan impressed him the most: whereas Ernst & Young employees tended to be flowery speakers who knew how to tell you what you wanted to hear, Jan was blunt. He didn't have a penchant for bullshit. He said it like it was and expected the same kind of bluntness in return.

Jan worked at Yahoo for nine years, through the enormous rise and then through the slow, stuttering fall of the internet giant. Eventually in 2007, he took a year off and traveled through South America and Central America. During this time, he applied for jobs with Facebook and Twitter. He was rejected both times.

So he used about $400,000 in savings from Yahoo to start a new project: a messaging app that he called WhatsApp. He chose the name because he believed it was similar to the popular greeting, "What's up!" After building a base of about 250,000 active users, he brought his old friend and colleague Brian Action aboard as a co-founder.

Together they undertook the journey of what is now one of the most captivating startup stories ever. Between 2009 and 2015, WhatsApp went from being nonexistent to having over 900 million active users, and is becoming the largest messaging app in the world. Additionally, it sold to Facebook for $22 billion in 2014.

When Jan signed the papers that would make him one of the richest men in the world, he didn't do it in the Four Seasons or at Facebook Headquarters, and he didn't have camera lights glaring. Instead, he returned to the nondescript building where he once stood for hours waiting with his mother for food stamps.

There, out of the limelight, Jan penned his signature. In that moment, he completed a circle that was about so much more than teaching himself computer networking skills from used books, or even building a successful business: it was about turning the tables in his life and offering purpose and meaning in even the hardest of times.

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Published on: Oct 22, 2016