There are ready-made resources in universities, so learning efficiency is high and detours are less. Even with poor qualifications, you can learn a lot quickly under the guidance of teachers, and you will get started much faster.

Self-study basically depends entirely on oneself. People with weak understanding rarely learn the essence. The main thing is to find learning materials by themselves, and no one gives guidance, so they often take detours, waste time and get started much slower.

In short, for the average person, the efficiency of self-study is lower than that of university.