TOSS: This dentist built a $2 billion Korean start-up — after 8 failed businesses along the way

Seunggun Lee, founder and CEO of South Korean peer-to-peer money transfer app Toss.

As a dentist, Seunggun Lee was used to filling holes in people’s teeth. But when he spotted a gap in South Korea’s banking industry, it was too blatant to ignore.

It didn’t matter to him that the idea was illegal at that time.

“I thought this service should exist in Korean society — regardless of whether it was legal or not,” Lee told CNBC Make It.

The young entrepreneur was hardly risk-averse, after all. Something about quitting his steady job as a dentist and pumping $400,000 (a 50/50 combination of his own savings and bank loans) into a “bunch of crazy ideas” gave him a certain brazenness.

A money maker

Lee is the founder and CEO of Toss, a South Korean money transfer app which last year became the country’s first $1 billion financial technology start-up.

He started the business in 2014, when similar peer-to-peer (P2P) money transfer apps — such as PayPal’s Venmo — were taking off internationally. But the red tape in South Korea’s famously regulated banking system made such services effectively illegal.

“I was able to see a lot of products that existed in the U.S. and I thought: If this was available in Korea, then it’s going to be huge,” said Lee, now 37, who described the country’s transfer system as a “cumbersome” multi-step process at the time. But getting it off the ground took some convincing — not just of regulators and investors, but his parents too.