It was different in premodern cultures.

Back then a child could be contributing positively to the farm in a few years and don't need a lot of training because they want to do the same things people around them are doing. Power tools require a certain level of maturity and judgement, my son was able to pick up a hoe when he was a toddler but our tractor has a weight switch in the seat and we had to make him wear a backpack with weights in it to drive it for the first time. (We even had a small adult woman living at the farm who was too light to trigger the switch.)

(My son didn't make a positive contribution, however, to the family business, a riding academy, until his mid teens. Until then he was always a little resentful of the horses since they were the reason his mom was often not around. Then there was that day he was roughhousing in the barn, a behavior the horses can find a little offputting, and he realized that one horse was taking an interest in his activity and that got him to recognize the social intelligence of horses... Before then we were worried about who would cut the hay when the farmer who does it retired, now we are not.)

Contrast that to the current day where children are an economic cost up to high school graduation if not college, grad school, etc. and whether or not kids go to college they often seem to have an adolescence that extends into the mid 20's.

Back in the day a huge family was your retirement, now we have social security and stocks and bonds (which are still dependent on demographics.)

I've known a few people who have had huge families (10+ kids) in the modern day and they have a very different mindset. It's not as much work and cost once you reach a certain point as the older kids help take care of the younger kids and that gets around the "parents are not gods" problem that are talked about in

https://www.amazon.com/Parent-Effectiveness-Training-Respons...

also there are a lot of hand-me-downs and other synergies. (Although my dad was quite bitter about getting hand-me-downs and sharing the bed with his brothers...)

A lot of the increased "standard of living" is not the things we think are optional (and "consumption") like the iPhone and the vacations, but rather the things that we think are necessary (and even "an investment") such as health care, a house in an expensive neighborhood with a good school district, etc. Remember this Liz Warren classic

https://www.amazon.com/Two-Income-Trap-Middle-Class-Parents-...

The Two-Income Trap is a great book on this topic: https://www.amazon.com/Two-Income-Trap-Middle-Class-Parents-.... Try to ignore the cover, as its content is excellent and the book isn't a partisan jeremiad.

Elizabeth Warren has an interesting take on the issue in the book "The Two-Income Trap"

https://www.amazon.com/Two-Income-Trap-Middle-Class-Parents-...