Because it was normal to have 2-4 kids in most families back then but your kids see the toll it takes on you and they ask questions which affects their perspective on how they either raise their own kids or whether they even choose to have anyone. A reason I don't want kids is not just because of my low fertility but because I saw how much stress it put on my mom and how I ended up raising my own siblings with her and am now raising my nephew. It taught me a lot harsh truths about marriage and I know I'm not the best so rather than waste someone's time who wants kids and a happy marriage that I couldnt provide I left it be. And I agree there are a lot of kids out of wedlock. But having kids does not hold a family together or fix a slowly dying marriage. If not a lot of people want kids it's not always because of a selfish mindset but because things are becoming increasingly stressful to where having a kid and getting married are so far on the back burner they might as well be nonexistent. You can barely buy a house these days even after getting a well paying dream job and working there for 10 years. And they're starting to pretty much penalize you for having kids by making it so disciplining your child is discouraged cause it's abusive, they make it expensive, child care is more expensive, busy work hours and your kids miss too much school? You can literally be fined and even arrested for it in the US. I wouldn't want to have a kid in these kinds of conditions either