I mostly agree with you, as a person who went to a middle-of-the-road public school.
I will point out though, anecdotally, my spouse went to the highest tier of public school in our city. She has a good balance of "seeing the world for what it is" while also having an edge of being personally networked to a ton of folks who are rich, well-connected, and capable.
I look at the friend groups I built when I was a kid, and then I look at hers.
- My old friend groups are all stuck in a range of poverty to lower-middle-class.
- My spouses friends are all doing very well for themselves, live all over the world, prestigious careers, active hobbies, highly intellectual, cultured, etc.
It's a stark contrast.
There is something to be said for ensuring your kids go to the best schools possible. Those early networks are pivotal in forming an above average life.
Competency is secondary to connection.