Not at all true,
I went to an awful secondary modern school in the UK,
Ended up earning so much money I couldn't spend it every year.
My UK daughter attended one of the worst schools in the UK is now primary pharmacist at a top London hospital. She earns a shed load of money.
My Thai daughter who attended a Thai government school (now 24), has a decent career in logistics 20k + accommodation.
My niece who attended government school in Nan (now 26), is regional manager for Lotus, 25k + car.
If you had children you would understand it's the kids drive and desire to achieve that earns them money. If they have no drive and desire, they will drift, get pregnant, take drugs.