Yep, it is the culture.
I've been lurking in this subreddit for quite a long while on multiple accounts, I'm a natalist myself and a young atheist woman who wants to have multiple children of my own. I've never posted. I'm sorry if this post makes no sense, it's more of a very long rant than anything about things I've observed. Excuse my English if I make any mistakes, it's not my first language.
Here's what I think has led to people not having children.
The richest countries in the world today are having the least kids. We live in the most comfortable time in history. Not to say that the housing crisis or inflation isn't a factor (it is), but I think it's overplayed.
People have always had kids, despite of all the wars in the world, all the famines and colonialism, despite poverty and despite illness. They've always had children because in their minds, children were a blessing and the future. From the rise of humanity, people have had children.
We live in a culture that thinks otherwise. Children are seen as something that hinders your freedom - hinders your possibilities to travel, drink and indulge yourself in certain activities. Not only do parents view their possible children as burdens, but OTHER people view their children as burdens. I remember my grandparents often being happy to take care of me and my brother and to take that upon themselves, but I'm not quite sure that a lot of old people are like that nowadays.
Many people have no sense of duty at all - not to their family, not to their country, not to humanity, not to any higher power, to no one but themselves. I think that a large part of this attitude has to do with feeling "burned" by society. A lot of people feel betrayed and hurt by society and other people and therefore do not feel that sense of duty that some people would feel in the past. They feel oppressed by these structures. No judgment from me, I understand.
Social media and technology in general has had a massive impact - people are exposed to the worst version of other people online. Women are exposed to incel forums and boys who call them "hiplet foids" and proclaim themselves "foid destroyers" on TikTok. Not just any fringe guy, but actual teenage boys and young men who feel genuine bitterness towards women. While I am glad that women are more informed and could protect themselves, I'm also sure that most men are not nearly as evil as the internet portrays them. I think that the faceless social media format has emboldened some men to show their extreme prejudice towards women and it has motivated innocent boys and men.
Men are exposed to women who hate them proudly, who mock men under 6 foot and brag about being misandrists. When a boy and a girl used to meet organically before social media, they didn't use to have so many preconceived negative notions about the opposite sex. That's why they could communicate without being so suspicious of each other. People are exposed to so many stories of infidelity, violence and betrayal online that they don't WANT to date. Nowadays, there is a huge divide between the sexes. It also transfers to real life. People would rather text their AI chatbots.
Another unfortunate development comes from general anti-natalist attitudes - a lot of them from women. Go on nearly any pregnant woman's post online (especially TikTok) and you'll see people calling her "body horror", asking for "the girl with the list" (a woman on TikTok who compiles reasons to not have children). A lot of these anti-natalist attitudes seem weirdly motivated by aesthetics - women are so deep in the patriarchal obsession with looking perfect and young (yes, beauty standards have gotten way WORSE and some of the most beautiful women of the last century would be considered "mid" today), that they and SOME MEN view pregnancy as too much of a sacrifice of that beauty that provides so much privilege. I do not blame these women at all, social media encourages young women to be obsessed with looking good. That's why you have young men bragging about their amazing maxillas (I don't even know what that word means).
You'll also find posts saying that you shouldn't congratulate a woman who gets pregnant, that pregnant women don't deserve seats, that they don't deserve support, that they look weird or gross. I suspect these come from the low trust of today's society. We've been exposed to the evil of our elites, the impacts of our economic system and societal structure, therefore we don't know who to trust.
We have been completely atomized, even in our own families. We have been divided. People no longer even trust their own siblings. A lot of people interact with their screens more than they do with their family and friends. People used to join clubs, to be close with their neighbors and with other peers. Now we lack affordable "third places" where people are able to meet organically. They are also exposed to content that says that you should "chase the bag", that people on the top are lonely. They're taught to see rich people and celebrities as idols, instead of big and happy families.
Individualism is also an interesting development. Whereas before it seems to have been common practice to identify oneself with one's family, village, institution or country, nowadays a lot of people see themselves as a separate "brand" that operates according to a certain aesthetic ideal. That's why we get this idea of "performativeness". Visual-based social media like TikTok prioritizes aesthetic and "vibe" appeal, often achieved through filters, makeup, posing and surgery, over authenticity and a lot of people internalize the idea that authenticity is uncool, ugly, gross and too unedited. Having children might ruin that "brand", it might make one seem less untouchable or desirable. I saw a woman on TikTok saying that the best thing a woman can do for her "brand" is to never be seen with a man. I thought that it was very interesting that even interacting with a person of the opposite sex might ruin one's "brand", whatever that means. A lot of people view themselves as the main character, as very interesting and as very important, so they believe that being lonely is cool or makes you "mysterious". I've genuinely seen it in others.
An interesting development that I've observed is that a lot of people are also obsessed with feeling comfortable, especially after the pandemic. They stayed at home for so long that being exposed to people, talking to people, being exposed to anything new makes them nervous, irritated and uncomfortable. I've noticed that a lot more people are also uncomfortable with casual touch or casual conversation than in the past, I view it as a symptom of how lonely most people are. So a lot of people nowadays simply view children (who are loud and often messy) as annoying, unlikable or simply too much for them. A lot of people have started feeling such casual discomfort from just being around other humans that a lot of them label themselves "introverts" from what I've seen. Not to say that introverts don't exist - of course they do, and a lot of them, probably 50% of everyone! But as a former "introvert" (who actually turned out to be a severely damaged and burned out extrovert), I'd say that many of these introverts simply haven't had enough casual contact with people or social media has made any contact with real humans uncomfortable and nerve-wracking. Some people have expanded their "comfort zone" so much that they can't even handle being around children and demand what is essentially a child-free world.
A large factor is also, I believe, that we aren't exposed to pain or fear or death as much as in the past. Back when illnesses, wild animals and death were common, people might have not been as concerned with feeling pain or dying; it was inevitable. They would've been "hardened" by constant exposure to danger. I'd like to assume that they also weren't as afraid to be around corpses or dead people. Women might have not AS scared to give birth, despite the large risk. Very paradoxical.
As much as I wouldn't like to admit this as an atheist, I'd say that secularism is a also a large factor in the fall of the birth rates and that these secular values have even invaded into very religious countries. Religious values often prioritize community and conformity. Many religions - most of them, in fact - view children as a blessing, whereas atheism has no set values (it is just the lack of a certain belief - that god or gods exist), so a lot of people set those values for themselves instead. And a lot of people set the value of not having children upon themselves. Religion exists to offer people hope, and a lot of secular people are unable to cope with the lack of true hope or to the point where they start feeling depressed, hopeless or nihilistic. I was raised Christian and I for sure know how hard it is to cope with the realization that there's truly nothing and no one out there for you. It is a deeply distressing feeling to believe in no higher power and it can lead you to not wanting to have kids. At least religious people believe that they could be blessed and that humanity would be saved if they prayed and offered sacrifices.
Climate change is a huge factor. The first time I heard that microplastics are everywhere and that we can't do anything about it, I seriously questioned ever having children. When I first discovered the huge impacts of climate change, it depressed me to the point of not wanting any myself. The truth is that a lot of people believe that there is no future for humanity and that there's nothing we can do. That the Earth will kill us. It had led to so much distrust in the future and, of course, not having kids.
Another big reason is what I like to called "failed revolution syndrome". We, young people, were promised what is essentially a revolution. I think that there was a sense of hope in the 20th century - new ideas arose, communism and far-left ideas became popular as solutions to the failures of capitalism, feminism became a huge movement and so did the civil rights movement for both LGBT people and racial minorities around the world. Punk and other rebellious music styles and aesthetics arose with fresh, youthful energy that promised that if we all just rebelled, if we all just did what we needed to do, the world would become better. We were promised a better world through these movements. Instead, what the system did is it stole these movements and capitalized on them. Instead of true equality in legislation all around the world, women can now buy a t-shirt with a Venus symbol on it. Capitalism just stole what women before us fought for and it dangled it in front of us for sale. We were promised true equality, and yet now young men exhibit so many sexist attitudes and women's rights have regressed in many places, most notably Afghanistan.
A lot of people feel that since revolutions have failed, and they feel truly powerless. Today's atomization of humanity has left them disconnected from real human beings, to the point where a true revolution feels actually impossible. I've even seen some people saying that not having kids is what will save the revolution, because then the capitalist elite won't have someone to exploit. That's why they feel this despair, this lack of need for the continuation of the the human race.
I've also seen plenty of people who believe that humanity has also reached its "peak" of culture and excellence, therefore there's no need to continue it, because what will come afterwards (technological revolutions) will be way worse and destroy humanity.
The combination of all of these factors, I believe, is what has led to today's childlessness. If you have interesting observations, I'd love to hear about them in the comments. I'm sorry if none of this made sense, but I needed to get these observations out of my system.