How do you think these developed nations will fill vacancies in their nations and get cheap labor if the population of these developing nations is reduced?
The population of a country is not always a headache for a state rather it will give huge benefits. let's take the example of China, it's the most populated country in the world but still, its economy is stable not only stable but is in competition with the superpowers. The more the population the more will be the economic strength. This shows that population does not negatively affect a country's poverty. This population is not only beneficial for itself but for other country also like the developed country need labor from the developing country and in return these overpopulated or simply developing country needs technologies and much more if the developing country reduces the population then it consequences on the developed countries will be bad and they need to find another way like making robots, offering for the immigrants, increase the productivity of their workers. This will not increase their productivity but at the same time will create a headache like the immigrants create political and social issues, robots lead to job loss of humans and increasing productivity of their workers need huge investment in their training. So it is necessary to settle the things between these two classes developing and developed if they reduce the population it will create tension for them as well as for the developed one also.