When I arrived in China to study, I met many Americans who recreated in expat bars and complained constantly. Why the negative attitude? Living and studying abroad is hard! Perhaps they thought it would be as easy as buying a plane ticket. Some succeeded in their studies, some did not. What do 留学生complain about?
School.
Often, they didn't know what kind of school they were applying for and got disappointed.
Beurocracy.
Differs from place to place. Feels like a waste of time.
Life.
In a new environment, using a new language, in an expensive city.