Or. Hear me out. They're psychologically and cognitively advanced enough to know any of the following could be true:

1. They can't afford them/would be unable to provide the quality of life they would want for their progeny

2. They don't want to raise their spawn in the same cesspool with "the general public"

3. They don't want to pass down genetic disorders that travel in their family

4. They don't want to continue generational abuses due to ignorance of better parenting techniques

5. It's none of your fucking business how or why someone chooses to live their life and people like you who say that humans are nothing more than chemical and biological reactions to a predictable environment are clearly not part of the sapient part of this species. Perhaps you've regressed, or aren't even homo sapiens at all! Perhaps you're predominantly homo habilus! At least in terms of cognition. And perhaps we should be studying YOU for your cognitive abnormalities and shortcomings!

6. They're afraid of what the future holds and don't want to bring children into unnecessary hardship (politically, socially, environmentally)