now let me ask this: is Gates smarter and harder working in proportion to his wealth than Knuth ?
- having a good family
- having good environment that mostly ignored his stubbornness and let him grow
- how lucky he was to be good in math and engineering
- coming from a well off family
- having a mother to push him to outside of his comfort zone(She was also in various boards so could teach the politics of leading people)
- having friends that helped him get better at understanding the computers.
Being smart is only one parameter in his success, he wouldn't have been so good if they hadn't given him the chance to program at private school he went to for solving the school scheduling problem for example.
IMO Comparing Knuth to Gates is the case of apples and oranges, most important reason being Knuth was born in 1938 and Bill Gates was born in 1955, Gates was in his prime years when the personal computer revolution was beginning.