Sticky, we evolved to reproduce, and that involves certain primary urges such as eating and having sex. It's a basic fact of human existence and not something that can be simply stopped for lack of money. Most western 'advanced' countries are full of overweight people who can't turn off the eating urge, even though they are costing themselves and society a fortune and much misery by their behaviour.
Thanks to science, people can enjoy lots of sex without the inconvenience of reproduction.
They also often have state benefits which mean they don't need to reproduce to provide help in their old age.
Poorer countries don't have those luxuries.