Why do some people go bankrupt and settle in first-tier cities?

Young people are divided into two categories: those who move to bigger cities and those who stay in local or similar cities. Migration to a bigger city is usually in pursuit of a class jump. For example, even in the same profession, doctors in Beijing, doctors in provincial capitals and doctors in county towns are obviously different. Of course, such people who emigrate will feel hard, because it is too difficult to upgrade the class.