Idk where yall meeting these teens that are more mature than you, but I never met an 18 year old who i didn't think was a goofy kid. Sure I met some more mature than the average one, but they still thought and said some goofy kid shit. Hell, the mature ones only sounded fake mature by repeating some nonsense older people told them believe, because they're naive.
Perfect example is when you see one at the job that gets that small promotion, and some older higher up manager has them working themselves to the bone, going above and beyond their job cuz they have them thinking they'll one day work they're way up from the bottom to CEO. They're looking at everyone else as fools for doing only what they get paid for, but we're shaking our heads cuz we know they'll eventually find out they got played.