Nowadays, the amount of urban population is growing rapidly with more and more people moving to mega-cities. I believe that this trend is negative for several key reasons.
The amount of citizens is increasing firmly due to social and economical causes: rural areas are not able to offer enough job and educational opportunities, and that is why many people, especially young ones, tend to leave the countryside in search of better prospects for personal development. The main problem is that the cities are not prepared to become home for its growing number of inhabitats. The infrastructure and the housing does not change as fast as the population grows, so the problems related to the lack of essential services and resources may arise.
Moreover, due to the lack of housing the cost of living is getting higher, and that is why a prevalent part of the relocants end up sharing accomodations. It leads to the appearance of overcrowded areas where diseases and viruses may spread in a faster way. Another drawback of co-living and a big city life in general is a psychological pressure on individuals who do not have the opportunity to spend time on their own, which may lead to mental problems. Some of them, in opposite, feel loneliness even while constantly being in a crowd and have to struggle with all of the dificulties themselves.
A growing percentage of people are now bulding their lives in a big cities. In my opinion, the higher level of urbanization leads to negative consequences related to infrastructural problems, limitness of the neccessary resources and risks of health issues, both mental and physical.