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.