There's no ego in Zego! And so when Estonian-born Sten Saar replaced his co-founder in the top job, there were no recriminations. Instead, the insurtech, which offers policies from 1hr to one year, has boomed, becoming, after its most recent fundraising, a "reluctant" unicorn. It's not Sten's first success: he founded his first company - notepads with study aids tucked into the covers - when he was just 18, growing it to $1m in turnover. In between, though, he had to learn some painful lessons, including why it's not always a good idea to get your father to mortgage his home to provide you with capital.