First, there are more opportunities in a big city. It is often said that people do better when they get appropriate background, so if you are well educated and your aim is to earn a lot of money, a big city will materialize your dreams. For example, living in a small town in Nepal, my best friend's father studied Bachelor of Art 40 years ago when the literacy rate in that small town was very low, and only the people belonging to prosperous families were studying. After completing that degree, he did not get any jobs that he liked, which was because of the lack of opportunities in that small town. The jobs that he was getting were blue collar jobs, and he did not wanted to do those jobs, since an advance thought was shaped by his degree that he would get a good job after its completion. So, he does not work as a blue collar worker. He did not think of moving to a big city for some reasons, and as an alternative, he opened his own shop in his place of residency. Although he earned money with that business, but not the way he liked. This experience made me think that even after having an appropriate quality, he was unable to get jobs he wanted because of lack of opportunities. Consequently, a though came to my mind when I heard it from my friend that probably opportunities are the reasons for big cities being dense.
Second, a big city has many facilities. In the lack of better facilities, lives are not as luxurios as it should be, and people sometimes bear resentful experiences. For instance, my friend who is from a small town of India told me that his pregnant sister was giving birth to a child, but the only hospital