Are population problems to be feared?

Living in a capitalistic city, most of the people rank their career above all the other aspects - starting up a family, forming strong bonds with friends and maintaining good relations with their neighbours. Yes indeed, earning money is important but isn't it a bit myopic of them to do so? Being myopic is not something to be proud of, it only seems to the people around you that your awareness to the main concern of everyone is very little. The main concern of everyone is of course the country's replacement rate that we faced at the moment. In some countries, they faced ageing population, while others either faced overpopulation or under population. In these countries, their government had been constantly thinking of strategies to solve these problems. To a limited extent, these issues would be feared, but in my point of view, this phobia would be greatly reduced as more and more policies were being implemented. What I mean is that with these policies, the problem will be better dealt with. In order to consider whether it is something to fear, we need to look at four groups of nations - the developed countries, just developed nations, developing nations and the underdeveloped - as they will give us a guide on how this predicament will be resolved, leading to us not supposed to panic over this situation.