Generally, populations with higher birth rates come from poorer countries or communities with lower living standards. Israel is the only major exception, but once you analyze the social strata it becomes clear why: higher-income groups still have lower fertility than the religious ones (especially the ultra-Orthodox and Arab Muslims) by a wide margin, even though the higher-income groups still have higher birth rates than other OECD countries. This creates long-term strains on society.
Another interesting fact is that groups with higher socioeconomic status (SES) tend to have lower birth rates. If SES correlates with IQ, then there’s an uncomfortable but politically incorrect implication: the smarter groups are having fewer children, while the less advantaged groups are having more. A few generations later, it’s not hard to see where this leads — human intelligence may trend downward. That is simply evolution at work.
Climate change, wars, pandemics, and natural disasters won’t wipe out humanity; we’ve survived all of those and recovered. But demographic collapse driven by high living standards is new territory, and I am genuinely, deeply worried.