system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the decrease of population growth in countries like Japan considered a bad thing? Shouldn't it be the other way?

I understand the need to have new generations of young people to keep the country going, but isn't overpopulation a bigger problem (like in China or other countries in Africa)? Also, if they need young workers, couldn't they get people to migrate to Japan?
gpt
The problem with Japan and many countries like it is that they have a society that is build up on the fact that the young will carry the costs of the ageing population. With the ageing population becoming too big, that is no longer possible. Is immigration an answer? Well, it can be part of an answer, but it is often not that simple. They don't all need unskilled workers, they also need skilled ones. There is not a huge supply of these. Plus there is the issue of not being able to speak the language and understand the Japanese culture. Which can be solved by education  but you'd need people open for that education and again it costs a lot. 

(this is not even taking into account that most countries don't like huge masses of immigration, and Japan especially is pretty bad at it.)