For your own reasons, the responsibility is great.
Many college students don't just attend classes at school. They also have a lot of things to do, such as part-time, starting a business and joining a club. Moreover, many people like to wait until the exam to study, so they don't spend their spare time in class and then study by themselves.
Like to chat and play.
Many universities have the largest number of students during classes, and many university dormitories are not together. In class, they are used to playing and chatting together, so they will cherish playing with friends in class.
The third point. The teacher lectures too fast.
There is no order for university teachers to give lectures, not every chapter. If you don't pay attention to the class carefully, you won't be able to catch up with what the teacher said, and you will be very brain-dead. You will always think about this problem, and then a lot of lectures will pass, so many college students like to teach themselves.
The fourth one. Pay attention to initiative in learning.
Many college students attend classes for a purpose. If you study by yourself, you really want to learn, so the efficiency of self-study is higher than that of attending classes, so college students like to study by themselves.
External cause
College is suitable for making friends.
College students go to college to make friends. In order not to repeat a grade, they can choose to study by themselves, which is more efficient, so they make full use of their time with friends to make friends.
Environmental impact grade
There are many people in the class who don't attend classes. Being influenced by others will also affect your class. Slow and complicated environment will affect people who want to study, so they choose not to study in class and choose to study by themselves.
These are the reasons why I think college students don't study by themselves in class.