Microsoft was founded in 1975. 10k hours is 5 years of 40 hour weeks. I think it's fair to say that he was working more than 40 hour weeks, so by the time MS

Microsoft was founded in 1975. 10k hours is 5 years of 40 hour weeks. I think it's fair to say that he was working more than 40 hour weeks, so by the time MS rose to dominance, he'd almost certainly spent over 10k hours at it.