You say people are egotistical and selfish to not have kids meanwhile at the start of your comment, you mention, having children was good idea so they could be used as working force — you realize how absurd that sounds?
Why absurd?
That was one of the main purposes people had lots of children in ancient times. People lived in countryside and needed abundant workforce to plant, gather and to feed the animals. There weren't automatic procedures to make it for them. Then within time, the number of children per family have been decreasing, until the point nowadays there are many people who don't even want to have a single child.
If it wasn't for this concept of family, probably those people would starve, unable to keep all the daily tasks completed. Then there wouldn't be anyone here today to claim how absurd that was...
That is sort of true, because farmers of the time, mostly did not even have enough kids staying alive. No matter how horrific that sounds, you have to remember medical world wasn't as improved as todays, and that meant a lot of people died at young age, the rate of people who didn't see even age 5, was insanely high. So they had to keep having children, enough so that they could grow up to help with the farm or whatever they were working on.
And even back then, even in those ancient times, people like senators, or whatever city job you had, didn't had that many kids, because they didn't need that many kids. Plus, protection wasn't as easy as today, so every time you be with your spouse, there was a chance of pregnancy, higher than today.