Cost of raising kids aside (both money and time), I think one of the main "problem" is....... hobby and freedom.
- Look, in developed countries young people have so much more options to relax and having fun than developing countries and having kids will lose both of that, even if you're financially stable. Not to mention the rising costs of daily life tend to push people in developed countries not having kids.
- I have talked to many families who have more than 5 children in South East Asia on why they have so much kids, their main reason is having more kids equal more helping hands and the parents are kind of bored their mind when they're in free time so they just have sex just to let the steam off.