As I've gotten older, I've gotten more used to the opposite idea:
Relative to other people (which is implicitly the metric we are using here), you are really smart.
Why do I think that? Because of the data.
The data is pretty solid that, whenever you survey the population, the level of intellectual sophistication is extremely low.
So low that many of the words I'm using in this comment would not be understandable to a significant chunk of the population. So low that, while knowing how to do a wordy math problem is table stakes on HN, knowing how to solve (x+5)*3=21 places you in the 'elite' of the general population.
It's got nothing to do with how we feel about it. It's just a fact that, when we look at the problems that 50% of the population cannot solve, the bar is shockingly low.
So based on that, yeah: the people who are reading this, who know how to write a 'for' loop on a computer, who read way above a 6th grade level, who could say 'yes I know what an imaginary number is', are really smart.