I would posit that you learn as much from success as you do from mistakes, if you sufficiently analyse them after the fact. We just tend to analyse and post-mortem mistakes more than we do successes. If I think of mistakes I made in hiring or people management, for example, the core learnings were more about people's skills and personalities than anything else. Things I didn't know prior, or should have asked about or tested, for example. Though making the decision and seeing the consequences of it, I learned things.
A related concept is the "handicap" in amateur golf. One player is accepted to have an advantage, so they get extra points coming into the game that help to balance it out. It is still fun to play for both players and now the outcome is not a certainty.