Except that we were all 17 once, too, and thought we had just as good a grasp on the way things worked as anyone else did.
Then ages 22-25 happened.
The problem with that age is that your brain isn't developed enough yet to comprehend how much your own arrogance blinds you. And yes, everyone is arrogant in some way at age 17.
I think you're confusing the terms 'brain' and 'mind.' I don't actually know if non-physical
thoughts are reducible to physical
brain states (the materialist would most certainly hope so), but I am also not sure if that's the most problematic assertion in your post. Before someone strawmans me, I am NOT denying the connection between the brain and the mind. This topic is better suited to the philosophy forum, so if anyone is interested in idealism v. dualism v. physicalism debates, I'd be more than happy to contribute to a thread.
I find it odd that your sentiment is, "arrogance is blinding, and everyone is definitely somehow arrogant at 17." Perhaps I'm taking you too seriously, but this is not a valid argument at all, you know.
However, allow me to digress. I am sure when 22-25 happen to me, I will definitely think of my 17 year old self as an idiot. I already think of my three to six months ago self as an idiot, so years should make a huge difference. An interesting note is I've always found people in their early 20s to be unconscionably pretentious and arrogant, whereas I've always perceived teenagers to fundamentally lack wisdom and foresight; and they thereby seem foolish/immature/reckless rather than arrogant.