The following is a description by a professor of Sinology (German) at Ruhr University in Bochum.
Among the undergraduates majoring in sinology, 50% gave up before the end of the first semester. Only 10% of the students finally succeeded in getting their degrees. Among them are German-born China or Vietnamese.
So when you meet a foreigner with good Chinese, there are many losers behind him that you don't realize. His persistence shows that he has a strong language talent, or he is very interested in China culture, or China is very interested in him. Otherwise, he can completely change his major and change his main direction.
But for China people, learning English is another matter. English is a compulsory course for students in China, but the mainstream mode of English education in China is still to popularize English to the population at a very low cost through public schools. So for a large number of students, the only use of English for them is to pass the exam.
Here, I would like to praise China students who are studying in Germany. Most of us are not German majors, but have studied German 1 for two years in public courses or private lessons. Then we sit in the classes of undergraduates or postgraduates in German universities and compete with those whose native language is German. The final result is that the graduation rate of our China students is higher than that of the Germans.
Of course, there are also survivors' bias, because the average quality of China students willing to study in Germany is still relatively high. Moreover, for the family conditions of most students, we have no way out and must burn our bridges.