Some people smarter than other people. And those people, on average will get paid more.
I don't see a whole lot of rage when people talk about how it takes good people skills to get a lot of jobs. But the moment intelligence becomes a requirement, everyone suddenly thinks that's unfair, or there is no such thing as intelligence.
I don't deny that there are many factors leading to higher SV salaries, but intelligence is also a factor.
For example I came from a very ordinary middle class background. To the extent that I have more education and a higher salary than people with the same background, I attribute it to my intelligence. I don't think that makes me better than other people, even though I'm constantly told that having better social skills makes you better than other people. And I don't think that there is a level playing field either, but conditional on my background I still earn a relatively high salary.
The counterpart to the smugness you complain about is your moral smugness. And there is plenty of that on HN too.
Inference: 90% of engineers probably think they are smarter than average engineers
I do not think you can segment Engineers different from the society & Humans in General ... There are Arrogant people everywhere, those who think they are in some way better than others. Not just that, they think everyone else is stupid :)
One might also say - they're not smart enough to realize that they are smarter. [But this is another PoV].
I've known too many arrogant engineers to believe this is true.