What the phrase means
A game worth losing is not a celebration of failure. It is a standard for choosing where your effort belongs. If a game is worthy, then even honest struggle inside it develops the right capacities: patience, courage, discernment, sacrifice, and integrity.
If a game is unworthy, winning can deform you just as surely as losing. It can make you more dependent on applause, more fluent in self-deception, and more committed to incentives you would never consciously defend.