Bill Gates Says Startup Founders Should Not Take Weekends or Vacations in the Early Days of Building a Company He did say, however, that people can 'over worship and mythologize the idea of working extremely hard.'

Bill Gates worked weekends and never took vacations in the early days of Microsoft, but this is all part of the sacrifice of setting up a company, he said.

At an event last week with other business leaders, billionaire businessman Gates chatted to Eventbrite cofounder and CEO Julia Hartz about founding a company. As part of this, he spoke about his work ethic in his 20s.

"It really is true that I didn't believe in weekends; I didn't believe in vacations," he said, as TechCrunch reported. "I knew everybody's license plate so I could tell you over the last month when their car had come and gone from the parking lot."

Gates went on to say that while he relaxed somewhat in his 30s, he stands by his earlier sacrifices. "I have a fairly hardcore view that there should be a very large sacrifice made during those, those early years, particularly if you're trying to do some engineering things that you have to get the feasibility," he said.

He did say, however, that people can "over worship and mythologize the idea of working extremely hard," and that he doesn't recommend it for everyone.

Gates is the second richest person in the world and is currently worth around $107 billion. He cofounded Microsoft in 1975 and owns 1% of the business today.

In the same interview with Eventbrite's Hartz, Gates also revealed his greatest ever mistake: Not setting up Android. He said the failure to launch a competitor to Apple's iOS operating system was a $400 billion error.