Your argument assumes enough people will stop having kids that it will make a difference. My argument is that children should not be forced into the lives of people who actively don’t want them, and that people expecting to have them should do so more conscientiously. Some people don’t want children regardless of circumstances; others would have them if they could afford them. Maybe what you’re seeing in part is people making responsible decisions, not inviting children they won’t be able to feed or take to the hospital. You’re also seeing the responsible decision to not have an unwanted child. I’m probably more concerned about a stronger military power overtaking a country and installing its government than I am of any immigrants from anywhere. And that military action could happen even if I did push out a baby.

You’re also assuming - or implying- that reproducing is the only way to contribute, to show an interest in future generations. But there are teachers, artists, writers, volunteers, mentors, etc. who don’t have kids and who care very much about not only future people, but those who are experiencing this life right now. Having a child might even hinder the work they want to do.