Most coaches don't win superbowls, because it is extremely difficult to do. So, there is a whole slew of stats around coaches not winning superbowls. None of them say much else besides the fact that superbowls are extremely hard to win.
Only 35 coaches have won a superbowl. Of those, only 14 have won more than one. We are talking about a rare thing. It puts the greatness of dynasties like the Patriots into perspective. What they did was so improbable, it is nearly statistically impossible. And yet, we are in the midst of another dynasty with the Chiefs.