I can describe my experience, but you need to understand people's biases. My bias is that I always liked kids. I enjoyed playing with nephews and nieces. I now work with children and have 2 of my own kids. The decision for children doesn't come about in a vacuum. I had a wife who wanted kids too. I had a stable job and felt ready. Even then I had no idea what I was in for. Kids put major demands on your time, money, energy, patience and marriage. I have one child which some might call "a difficult child" and one who is very demanding (as expected for a "normal" child). This is definitely life on hard-mode. Children really force you to face your own issues and get over yourself. It has been great for me. I wouldn't change a thing about my "difficult" children. Giving them a good life and catering to their needs is an undescribable satisfaction and fulfilment in itself. I'm learning more than I'm teaching them. I wish work didn't take so much of my time and energy so I had more for them. I asked my wife if she wanted to work full-time, because I would happily stay at home or work part-time and spend more time with the kids. I can't get enough of my kids and the time you get at each stage of their life flies by in an instant.
That's starkly in contrast that with large proportions of Lemmy (and Reddit) which have quite vocal child-free populations with a very individualist ideology. Everyone's circumstances and biases are different.
Edit: People also tend to be more open about defending their current position rather than expressing regret (i.e. had children and hated it, or didn't have children and regretted it); both of these populations exist and tend to be quieter because of social stigma.