The problem is less "you gotta be a teenager to start getting good at X," and more so "teenagers have an incredible amount of free time and unsullied passion to expend getting good at a thing." I work a majority of my week, and don't have the energy to expend afterwards on learning a new thing, nor do I have the passion left to learn it because I'm always thinking in the back of my mind, "this will take months or even years to get even just decent at," and I stop because I can't work up motivation to continue once it reaches the conscious part of my mind.
Teens also are just expected to do a variety of things, and often can find people or clubs to help them out. Where am I supposed to find someone to help me learn music for example when I know literally nothing? Sure there's clubs, but I doubt a bunch of adults who already know what they're doing don't wanna spend a few months getting me up to speed. There's classes, but those are expensive and especially add up if you want multiple of them. Sure there's a plethora of YouTube videos, but that's not gonna work for all people (and most of them require you to have a bare level knowledge anyway, even the ones labeled ABSOLUTE BEGINNERS). As a teenager, you can just go join your schools music club and be welcomed because you're expected to not know anything, you can ask a music teacher for help, you have access to way more resources than the average adult does.
I don't mean to be a downer, but that's just the reality of the situation, at least for me it is. I wish I could spend my time actually learning something, but not everyone is lucky enough to be born with a fiery passion, or a will to just say fuck it and power through having no energy or time to dedicate towards something.
