India, Feb. 10 -- Microsoft co-founder and billionaire philanthropist Bill Gates has shared that he used to work 80 hours a week, writing code for his company, even after accumulating immense wealth. Speaking to CNBC Make It, the 69-year-old tech mogul admitted that he did not feel truly successful until more than a decade after becoming a billionaire.

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Gates, who co-founded Microsoft in 1975, said he only felt comfortable about the company's position in 1998, 11 years after taking it public. By that time, he had already become the youngest billionaire in history, according to Forbes.

"I wouldn't say that I felt comfortable that we were succes...