Correct. That is precisely what happens. My experience is this: 80% of kids, regardless of their genetics or the parenting skills of their parents, start out in life pretty normal and with at least a modicum of intelligence. They then get royally fucked-up by going to school with a vocal minority of little bastards, who are allowed to do whatever they like lest their fragile egos should be bruised. Simply allowing those 20% to fail in isolation - which they would do regardless - allows the remaining 80% to succeed.
Those parents who care not one jot about their children’s happiness or future life experience will not send their children to schools that serve the needs of parents who do.