Is it “selfish” to not have kids?
No, of course not.
The accusation of selfishness implies that it sucks to have kids, and not having kids is better, and therefore "selfish." -
You only get one life, and you have the right to enjoy it.
The accusation of selfishness implies that it sucks to have kids, and not having kids is better, and therefore "selfish."
Because people without kids enjoy their lives more.