Being more hard working and more intelligent than the competition won't get you very far in anything except purely practical work.
Those definitely aren't things that make a manager successful. Being approachable, being on the side of the people you're managing, willing to pass on the credit for wins and take responsibility for failures, being willing to make hard calls and tell people 'no' when they're unreasonable etc are the nice things that make a manager a good manager. Being selfish, ruthless, and willing to burn bridges to get further up the ladder are often useful skills too, albeit from a slightly nastier perspective.
Management is psychology and politics. Those things don't require much hard work or intelligence. (I'm not calling all managers stupid; managers need 'street knowledge' and savvy judgement.)