You don't even have to be "selfish" to not want kids imo. It's usually not for everyone and not preferring to have any is by no means selfish when the world's already populated enough as is.

Parenthood is what it is, it's neither the worst thing on the planet like some act like, neither does it suddenly solve all universal problems and give you a life full of meaning and suddenly bam you're the best and most fulfilled person alive like others say. It's somewhere in the middle.

Just like certain food groups or game genres, it's either for you or it isn't.