My brother is 19 years old, and when he was 13~14 years old, my mother wouldn't let him go out to play with his classmates.

that must be because his mother won't let him out. His classmates talk about him behind his back or face to face, which makes him unhappy. For the sake of his self-esteem, he decided to close himself.

the characteristic of playing mobile phone at home is that there is no goal, just muddling along. My brother has been at home since then because his classmates laughed at him. My cousin has been playing mobile phones at home for six or seven years every day, and he also goes out to play, but he doesn't work much without goals.

I haven't thought about how to solve these two situations for the time being.