One of the most inspiring success stories of an entrepreneur who rose from challenging circumstances is the story of Jan Koum, the co-founder of WhatsApp. Jan Koum was born in a small village near Kiev, Ukraine, in 1976. His family lived in a house with no hot water and faced anti-Semitic threats. In search of a better life, Koum and his mother immigrated to Mountain View, California, in 1992, when he was just 16 years old. They struggled to make ends meet; his mother worked as a babysitter while Koum swept floors at a grocery store. Despite these humble beginnings, Koum developed an interest in programming while still in high school. He taught himself computer networking by purchasing manuals from a used bookstore and returning them when he was done. This self-education helped him secure a job at Yahoo as an infrastructure engineer, where he worked for nine years. The turning point came in 2009, after Koum bought an iPhone and realized the potential of the then-nascent app store. He envisioned a new type of messaging app that would show statuses next to individual names of the people. Koum discussed the idea with Brian Acton, a colleague from Yahoo, and together they co-founded WhatsApp. The app's user-friendly interface and innovative use of a phone's internet connection for sending messages without SMS fees quickly made it one of the most downloaded apps worldwide. In 2014, Facebook acquired WhatsApp for $19 billion, making it one of the largest tech acquisitions at the time. This acquisition turned Koum into a billionaire, a far cry from his early life of hardship and struggle. Jan Koum's journey from a teenager immigrating to the US to becoming the co-founder of a globally dominant tech company is a testament to resilience, hard work, and the belief in one's dreams despite bleak circumstances.