There are many ways one can be smart. Having an intuition for solving complex problems is not the same trait as having a good memory or controlling your emotions or being environment and self aware.

Many are overlapping traits sure, but someone that has them all, can easily be the worse at each one, when compared with others that excel in that area. This is why you see so often brilliant people doing idiotic stuff.

So, "everyone's stupid" is a matter of alignment, in the areas you're best, where you can judge best, few around are better. Which can be true while still not making you the smartest person around in all ways.

I don't agree that this iuis an indicator of any kind of intelligence other than social intelligence (e.g. don't say stupid things that affect your life, in other words socially intelligent people keep it to themselves)