I only started feeling more mature when I entered college, compared to not just people my age but even the teachers and the oldest students. They always showed signs of lack of self-control, not thinking before acting, feeling entitled to having what they wanted from others, etc. It got so awful to the point where I questioned my safety.
Aside from school, I feel like the mature one in my family and often run after my parents. But my siblings in comparison are too much to handle and I tend to just avoid them.
When I was in middle and high school, I just felt people often cared about silly things.. their reputation, what they think they should be doing, etc. rather than enjoying their lives. They made trouble out of garbage and they hurt people in the process. They were the cause of their own self-esteem issues. I also found them to be 'dreamless'... They didn't have to have ambition or career goals, it was more that they cared or were passionate about nothing and just living their life as a role. And because of this, I couldn't really connect with anyone... It was like there was nothing to connect to, inside each person.