It comes down to IQ grade. IQ denialism, as it was suggested by Haidt, makes about as much sense now as New Earth Creationism in biology, there is simply so much evidence.
Grades are just proxies for IQ — which most parents are too dumb to conceive of.
IQ isn’t strictly a number, it’s a grouping with an error variance. The Binet IQ was intended for school application ONLY – to ascertain how the child’s learning process could be assisted by teachers at each stage (level of work compared to their chronological age), look at modern Sets for the truest application.
If you’re at the top grouping possible for a human, as an adult, A+/200+ High Genius or basic polymath, you have all the choices. And who doesn’t want options for their child (and by ego extension, a compliment to their own genetic material) but the further down the pyramid you go, the more restricted your future prospects. These are facts.
If you wanna be an astronaut, you’d better be making As and Bs. Just because you sat in the same classroom for decades doesn’t mean you’re equal in life quality potential or entitled to the same things as adults (public school kids and pronounced failures regardless of family fortune are the amusing example).
Telling children they all have equal potential may seem nice, and the Nurture Brigade of modern teaching insist it’s fair (if you are ignorant of their status yes, in case) and necessary (see former) – but it traumatizes the average and below-average children and sets them up for a lifetime of suffering, and probable mental illness (hark! Freud’s ghost laughing in the distance). Children blame themselves when they fail or something goes wrong. Fine if the changes needed are within their control… this is rarely the case here. The self-esteem movement formed to prevent mental illness, theoretically as a shield against it, and now… many young people are popping pills.
This lie about potential doesn’t even sink in (because for this to apply, they are dumb) when they’re adults. Millennials are miserable. They see their age-peers succeed and assume (all else being equal) there is something they can do about it, and feel entitled (+) or wronged (-), that their own course isn’t going the same way (a few come up with lies i.e. their competition is cheating, or secretly evil).
n.b. IQ is computed by age, so child ones are unreliable although age 11/12 is highly correlated, it’s best to get retested as an adult and expect a small dive. Many supposed prodigies fail on this count because they were merely ahead of the curve at school (by external factors of socialisation, see Gladwell’s Outliers), and not genetically ahead (permanently ahead). Hence, prodigies seem to burn out, when in fact the fakes (harsh but true) merely crash into the wall of their genetic potential. Elements of the modern school system e.g. obedience to popular belief, lack of imagination and rote memory dependence also contribute to this false-flagging of intelligence, as it were, rewarding traits which are, in effect, the anti-genius. Lies on the other side of the IQ fence.