If you’re always focused on winning and losing, then in the long run, you’ll always lose, because whether you win or lose is inherently tied to your sense of self worth. Not to mention that your relationships with others will always be predicated on you gaining the upper hand, whether overtly or covertly.
On the other hand, if you focus on win-win relationships, your life will be filled with harmony, and you’ll be rewarded externally, and intrinsically, because of how you behave.