Quote from IShopAtPublix:
You know, for a time the British thought they were a superior race guided by Providence. They were delusional. Nazis thought they were a master aryan race, they were delusional. Romans thought they were superior, they were delusional and got overrun by the "barbarians".
Brits did not believe Japanese had it in them to attack them. End result British possessions got overrun in the Pacific and if not for USA, Brits would never get them back.
When you are talking about long term of a human race you are frequently talking about hapenstance. If some Warlord saw lightning great many years ago and decided it was a product of divine intervention and killed or victimized anyone who thought differently that would have long term consequences.
People in South America, for example, did not have access to horses before horses were introduced by the Conquistadores.
An infinite amount of factors including diseases, silly religious beliefs, access to certain livestock, metals, etc. could influence an outcome.
If there was an inherent gap between blacks and whites, blacks could not be educated period (blacks by and large had no access to education in africa for centuries). We know they can, which means there is no inherent gap.
US is paying the price for the stupidity, lazyness, debauchery and degenerate behavior of slave owners who wanted their fields tended for free.