My theory is we've become sufficiently entertained that we could easily envision never becoming truly bored of our lives. There's a constant flow of social media, games, content to stream, etc. If you feel a void in your life, a lack of purpose, you may choose to invest in a child. But, it's a very expensive hobby which requires a ton of time and dedication. Like all long-term investments, there's no reasonable way to know if your ROI will be above your desired threshold when you made the investment.

I'm in my 40's and when I was born my parents had newspapers, radio and 3 channels on the TV. The channels stopped airing content after midnight. They'd have been bored to death if they didn't have kids.

Indeed, and back before the modern day, people really only had sex as their main enjoyment, which they now don't really need anymore. Of course more kids were conceived in the past versus now, they were bored out of their minds otherwise. Once we get virtual worlds with fully realistic sensory input, I doubt people will really have kids at all anymore.