They did poorly. Even experienced strategists tended to underestimate the power of forgiveness and reconciliation. The superiority of the Brazen Rule in such tournaments was discovered by Axelrod and described in his remarkable book The Evolution of Cooperation. Among other virtues, it breaks out of unending vendetta. The Prisoner's Dilemma is a very simple game.
Real life is considerably more complex.
Do not envy. Be neither a tyrant nor a patsy. Retaliate proportionately to an intentional injury.