Not to brag (is it even possible to brag through an anonymous throwaway account?), but throughout my schooling I skipped or skimmed most readings and avoided doing the homework, or copied it off my more diligent classmates. But I still got perfect grades in high school and graduate school, outperforming classmates who worked much harder. In undergrad, I had mediocre grades only because I just didn't do the homework and often turned in term projects many days late, but based on test performances, would have also had near perfect grades. I have a bad work ethic which holds me back in other ways, but I'm still near the top of my field for my age bracket. If I hear something once, I understand it and remember it for life. I don't mean memorizing lists; I mean learning how something works and why and how to apply that knowledge.
The entire modern dialectic around intelligence is emotionally driven. Dumb/unsuccessful people want to believe that smart/successful people just got an unfair leg up in life. And smart/successful people want to believe that anyone can achieve what they did if society helped them enough. We don't want to accept that some people are born with what it takes to become elite and some are born without it and will never have it.
>but the major aspect of being smart is about wealth and educational inequality
No, this is flat out wrong. There has been so much research on this, and intelligence is both highly predictive of life outcomes (controlling for wealth) and extremely heritable. If you take the biological kids of smart people and raise them in poor households, they still turn out very smart, much smarter than the biological kids of dumb people who are raised in rich households.
No. SAT is in fact fairly resistant to preparation. Not as much as some other tests, and not as much as the older versions of the SAT, but it's still largely an intelligence test.
The pay is shit, so intelligent people decide to pursue other passions instead of teaching.
Also, the profession seems to attract the kind of people who like to exercise arbitrary authority over other people. Not a majority of teachers, but a substantial minority.
Once I realized these things, a lot of negative experiences I had with teachers made more sense. For what it's worth, I also had some great teachers along the way.