Being boring is seen as bad to teenagers but really, it's not that bad.
(I say "mistake", but really it's just the natural consequence of not yet having a clear sense of self, which is perfectly normal at that age)
My friends don’t want to hang out with someone who is boring. Adults don’t want to talk to a kid who can’t show that they are mature and can’t provide experiences to back that up. Colleges aren’t going to admit a potential student who can’t an tell an interesting story.
There is too much incentive to not be boring in my current environment.
But once you're older, you want a companion, kids, strong ties to family and friends, and then you realize it doesn't really super matter that you're boring or not to the people who hold the keys to your future (admissions officers, teachers, professors, etc.), just that 5-10 people close to you aren't bored by you.
It reminded me of something I've read about the attitude among Math students at Oxford some decades ago - you were only cool if you we've shown effortless brilliance. If, on the other hard, you were working very hard to bring your math skills to a remarkable level, you were basically a rube.
The adult version of this advice would be "if you do what you've always done, you'll get what you've always got". I rarely regret taking the more adventurous route.
For me, this isn't about being interesting to others, but about making life interesting to myself.
I agree it’s not bad to be boring... but it’s not the only thing that /I/ want to be.