He can invoke the principle of "It's better to beg for forgiveness than to ask for permission." You're easily played if you go through life following rules as rules are being broken against you.
Even in kindergarten, in games during recess, the cheater gets the glory, the cheated pouts and cries and is told 'it's only a game.' But life, my friend, is always a game.
Being good doesn't make you a loser. Stress tends to make you a nicer person, but there is a certain type of "goodness" found in people with unsatisfied sexual desires (which is a kind of stress), and that is where "nice guys finish last" comes from.