Hypothetically I could memorise thousands of books, I could ace all my tests, earn tens of certificates and trophies and I still wouldn't consider myself as smart. I can memorise a bunch of stuff, but does that make me smart? Knowledgeable, sure. Smart, not necessarily. To me, being smart means being able to apply whatever knowledge you've gained.
So just because you don’t know a lot about a lot, doesn't mean you aren't smart.
Some of us can only handle (or only want to handle) being smart in a few, or one area(s). But we try to be “smart” anyway. We end up knowing a little about a lot and nothing about anything.
I am so for “broadening our horizons”, but if we reach the point where we can’t have a lasting conversation about anything what’s the point? While we are becoming more knowledgeable about the world that we live in, I think we need to remember to find that thing or those things that we are really passionate about, and specialise.
So that once in a while you can have a conversation that makes your eyes light up. And maybe, just maybe one day it’ll be your speciality in life.