First, traditional ideas are unacceptable.
In China, many parents have traditional ideas. They didn't have these things before them. With the development of society and the spread of new things, they can't accept these new things at once. They think playing COS is doing nothing. They think that wearing such strange clothes will only make their children different from ordinary people, which they don't want, so I think this is one of the reasons for their opposition.
Second, it wastes money and affects study.
In many traditional parents' ideas in China, reading is the only way out for children. When they have this hobby of playing COS, they will think it is a wrong hobby. This hobby is useless, and it doesn't help their study. It's a waste of money to play this game. From top to bottom, you need to buy everything, including hair, clothes, pants and shoes, as well as accessories. This is not a small expense, and when you have these, your parents will worry about you.
Third: fear of meeting incorrect friends.
When you start playing COS, you will inevitably participate in many comic exhibitions. In the process, you will meet many people and make some friends. Parents are not worried about making friends, but are afraid that you will meet some bad people and make some incorrect friends, which is one of the reasons why parents don't allow you to play COS.
In short, parents' opposition has its own reasons. What we need is to convince parents with actions. I believe my parents are still enlightened. When we take our own actions, when we don't let them worry, they will no longer object to us playing with these things.