One popular explanation is usually the scarcity of educational resources in China. In China, you work really hard so that you can out-exam the other students so

One popular explanation is usually the scarcity of educational resources in China. In China, you work really hard so that you can out-exam the other students so that you can get into some decent college. The gist is that China has limited higher-educational resource (so graduates on average do not come out that well) and a large population base (so people really need to work hard to fight for the little resource).