You're confusing an excuse your mom didn't like with an actual rationale. A rationale is a reason for someone to do something. It's empirically the reason giv

You're confusing an excuse your mom didn't like with an actual rationale. A rationale is a reason for someone to do something. It's empirically the reason given for this kind of behavior in many situations. We may not like that reason or think it's fundamentally the most mature way to behave - but it's still a reason. If you're saying it's illogical, it's not, game theory says that this kind of self-protective behavior is very logical when competing with other actors that are also being self-protective.