As an outsider to the world of elite private schools, is the idea that they will help your kid get a nice job even if they're actually just mediocre? Like, in m

As an outsider to the world of elite private schools, is the idea that they will help your kid get a nice job even if they're actually just mediocre? Like, in my head the logic goes "if you're in the top 10% of your high school class and get 1500+/1600 on the SAT, you can probably go to a cheap honors program at a public state school, and then you can pick from several tracks to make six-figure salaries". But maybe you need to be well-networked since preschool to work in finance or whatever if you're just of average intelligence?