In game theory, there’s a strategy known as tit for tat or in Nicky Case’s Evolution of Trust game, as the copycat strategy.
It holds that in a game of trust where over a series of moves, two players are given the choice of cheating or cooperating, the copycat will always cooperate unless the other player cheats. Once cheated on, the copycat will retaliate. If their opponent reverts to cooperating, the copycat will do the same.
Of course there are other strategies to winning a game of trust. You can choose to always cooperate, regardless of your opponents moves, you can always cheat, you can choose to retaliate more or less harshly when your opponent cheats or you can randomize your moves completely.
Over many games, adopting a copycat strategy has been shown to be more successful than any other strategy.
In other words, sticking to your principles and only cheating defensively, will ensure you win over time. It also builds trust.
If you don’t believe it, try Nicky’s game for yourself.