We’re both using personal information as our basis.
It seems to me, at first blush, that your students have not really made a decision. They are explaining why they are putting off a decision.
Those interested in the big picture could try to find some information on just why people ultimately choose to not have children. As I recall, there is some national group of people who chose to not have children. Those—among others—are the folks one needs to question to find out why they did as they did (or didn’t). Of course, many who made their own decision have not joined this group. It sure is complicated, seems to me.
Even in the absence of definitive information, I deplore attributing such a decision to selfishness.
It all comes down to what you value most in life.
Some people value family and children, and others value money, spare time, and personal freedom.
I have many single friends who travel all over the world, on business and cool vacations, and are childless.
I have struggled all my life to raise a family. Would I like to vacation in Greece or Spain? You bet. Would I trade my grandchildren for that? Never.
By the way, those single people are all liberals.
Even in the absence of definitive information, I deplore attributing such a decision to selfishness.