In 2013 he put $200K into Calendly, now worth $3B with 50M users

When entrepreneur Tope Awotona founded Calendly in 2013, he put his financial security on the line to solve a problem he had repeatedly encountered while working in sales: the frustrating back-and-forth involved in scheduling meetings. In an interview with How I Built This, Awotona said building the initial product was expected to cost a little over $200,000, forcing him to empty his retirement account and savings, borrow money and max out his credit cards. Eight years later, a $350 million funding round valued Calendly at more than $3 billion, according to TechCrunch. The company now says its platform is used by more than 50 million people.Awotona, who grew up in Lagos, Nigeria, before moving to the United States as a teenager, had worked in enterprise software sales at companies including IBM and Dell.