I've thought about this one.
A lot of people play the Game of Life(1) because they think that's what they're meant to do. Then, halfway around the metaphorical board, something makes them self-examine for the first time, and they realise they don't have to play. But because of the sunk cost fallacy, they can't quit. But if they can make their partner give up instead, then they "win".
1) As in Hasbro, not Conway.