This 52-year-old worked 90-hour weeks to save money for a restaurant. Now, he's worth $9.5 billion

Last week, Todd Graves entered Forbes 400 -- a list of the 400 richest people in the US -- and became the 107th richest person on it. The 52-year-old owner of restaurant chain Raising Cane's Chicken Fingers is currently worth $9.5 billion but when he was around 30, Graves worked 90 hours a week and sometimes, 20 hours a day to save money and to open his first restaurant.

In 1994, Graves travelled to Los Angeles to work as a boilermaker at an oil refinery. There, he worked 90-hour weeks to raise the money to fuel his restaurant dream, the company stated on its website. When he learned from a fellow boilermaker that he could earn even more money commercial fishing, the then 31-year-old went to Alaska and camped out for a month before landing a job on a boat to fish salmon "working 20-hour days in harsh conditions".

The idea of a restaurant chain that sold only chicken fingers occurred to Graves when he was in college at  Louisiana State University. He had pitched the idea in a startup-pitching assignment but had gotten the lowest grade.

“If people tell you something can’t be done, it makes you strive so much more to do it,” Graves had told students at Nicholls State University in 2009.