Slavery, gay marriage.

Gentiles didn't have be be discriminated against in order for Jewish students to start doing very well in Harvard a few generations ago. The distributions flipped pretty much as soon as entrenched barriers such as quotas were removed. The same was true for East Asian students in elite universities decades later.

Oppression of the Japanese after WW2.

Now name an instance where it was fixed by giving them much better treatment than everyone else.