

What sense does it make if you raise your population and everyone is miserably poor or on the edge of becoming poor?
There’s an overall negative correlation between wealth and fertility, so it’s not like the rich are having a ton of kids, either. Or even the societies with decent metrics on wealth or income equality, still tend to be low birth rate countries.
It’s a difficult problem, with no one solution (because it’s not one cause). Some of it is cultural. Some of it is economic. There are a lot of feedback effects and peer effects, too. And each society has its own mix of cultural and economic issues.
And I’m not actually disagreeing with you. I think there’s probably something to be said for cheap cost of living allowing for people to be more comfortable having more children (or at a younger age, which also mathematically grows populations faster than having the same number of children at an older age).
If you eat nothing but rabbit or other lean protein your body can essentially starve because it’s not getting enough fat and carbohydrates. But eating rabbits in addition to a diet that has fat from other sources makes the entire meal plan balanced enough to where the rabbit is a helpful/important part of the balanced diet.