There are also circumstances and other factors that may be unknown to you when you move to a new place (your first flatmate, the city you move in, the company etc), or factors you did not choose or had little control of up to some age (the area you grew up, the people around you etc) that can affect one's experience. The article's author also talks about that.

A person who moved to ostwestfalen or in a small town in eastern germany will probably not have the same experience as a person moving to hamburg (no offence to any of these places). A person moving as an intern to a relatively international environment will not have the same experience as a person who moves to a 100% german environment. It definitely matters how you act in your environment, but the environment restricts what you can get out of it as experience. Similarly, this applies to moving to any country, but also to where you were born.

Imo and ime people who do not get a good experience out of a country (the one they were born in or where they moved) is most of the times not about having unrealistic expectations of other places (they may have, but it is not the point) or they do something wrong, but due to a big chunk of factors and general character/compatibility issues that one has little control over, and may even be unaware of until that point. This holds for the "success stories" as much as the "failed" ones. It is hard to accept sometimes because having little/no control over stuff can be uncomfortable. The experience of different people can be different for things out of each one's control mostly.

In any case, getting different experiences in places out of where one was raised can always be helpful and help one grow.