If they're rational agents, then they should understand the results of the iterated prisoner's dilemma, and understand that screwing people over doesn't pay, remorse or no remorse.
Aside from the fact that life isn't a restricted theoretical game theory puzzle and rational doesn't mean educated (thus aware of prisoner's dilemma), this would assume that the people they're screwing over are also rational actors and are capable of cooperating.
You don't have to be aware of the iterated prisoner's dilemma. My point is that as a psychopath screwing people over, you should realize that this strategy is suboptimal. You will lose out to people who do cooperate.
He fucks you over and that is eventually a non-cooperation in an even bigger iterated prisoner's dilemma game.
Unless you willingly let him fuck you in the ass again, then his psychopathic strategy will no longer work on you, and you will at least not cooperate, and possibly retaliate resulting in a net loss. In fact, this is extremely likely because it's in your incentive now to disincentivize him from further fucking you because you want to send the proper signal.
For starters, it is a two player game. Secondly it will not always be crystal clear that you chose "defect" to your coplayers in the real world, since actions are subject to interpretation. Third, the real world is not a game of perfect information.
It is clear that you chose "defect" in the real world.. over time. It is in fact theoretically impossible to escape this consequence as time approaches infinity. Think about it, you are constantly leaving traces of you "defecting" and not leaving traces of not defecting. Eventually this catches up. This is also an example of the principle of karma, aka cause and effect. You can't escape fundamental effects of causes forever.