system
A chat on subreddit /r/NoStupidQuestions
human
90% of the population used to be farmers.  Children worked on the farm.  And the children took care of their parents when their parents got old.  So children were both a source of labor and a retirement plan.  So having a lot of children was beneficial.

Now most people work in "regular" jobs.  Children do not work.  So children are an expense, not a source of labor.  And children do not take care of their elderly parents.  Parents save for retirement - which is easier if you don't have children.

So children went from being a source of wealth to being an expense.
gpt
I remember reading this somewhere.

&amp;#x200B;

"People in those days had twelve children for many reasons. First, half of them would be girls, therefore useless. Out of the six boys, one would die of childhood illness, one would die trying to catch a runaway wagon, one would be killed in a barroom brawl, one would die in war, one would get killed by a thresher and the one that lived will take over the farm."