I'm an environmental scientist that worked in conservation for 6 years. Currently working on pivoting my career to teaching. I'm a mom to one and not planning to have more. Anywho, a lot of people don't see any threat to our planet. They get their coffee, they drive to work, they binge tv, they stare at their phones. The average person doesn't encounter issues with the environment or overpopulation except for the people working in the field of environmental data on overpopulation and how it affects the planet. Sure, it's on the news and you hear about it in passing, but I literally know no one even in the conservation field that is stressed about environmental concerns to the point of refusing to procreate on the moral grounds of helping stave environmental concerns due to overpopulation.

Also the fertility rate (hate that term because it's not indicative of what it truly is) is in decline.