I have read comments by women online that they had kids because they were afraid to miss out on the experience. They see it as one of life's important, meaningful experiences and did not want it to bypass them. I guess I would understand that if it were something you could undo, like a marriage.
It's just a fundamental difference in how they view the world, the same as how they don't see it as a "choice" but more of a natural thing that people are wired to want.
I can be curious at times about what motivates people to spend the best years of their lives focusing on someone else's life. Sometimes I do want to "get it", but only in the same way I want to understand a life choice or religion that's not my own. I find it interesting when these people say they've "tried being CF". In most cases that isn't true. They've been childless, yes, but only with the expectation that a baby is in the future, and every choice they make and everything they do is done with that plan in mind ("we're buying a house so future kid has a yard", "I've stopped drinking so I can try to get pregnant", "We're trying to see the world now before kids come"). That's not "trying" a CF life.
People should just shut up and mind their own business.