There is no massacre against white farmers in South Africa.

When are the murders of white South Africans by the black Bantu majority a widespread enough problem for you to consider it a massacre? Only if the black Bantu majority starts literally trying to exterminate them? I guess the lynchings of black Americans by white Southerners and the pogroms against Jews in the Russian Empire were also fine, they weren't getting exterminated after all, only killed in small numbers on the basis of their race, no worse than what's happening to white South Africans.

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If white South Africans have it so bad, they can always go back to Europe.

A lot of them are trying to do just that (and a lot more would want to but simply can't afford to move), only to get rejected by the governments of those European countries. Even the Netherlands, which is literally the ancestral homeland of the Boers/Afrikaners, refuses to take them in (while simultaneously being just fine with Muslim and black African migrants coming in en-masse).

Your argument would be more valid if they actually could just move back to Europe without restrictions, based on right of return or something. Of course you're well-aware they can't just move back to Europe, don't pretend you aren't, I'm not buying it. You just want them to be in a catch 22 position where they're neither safe or welcome in South Africa nor in Europe.

Imagine the outrage if someone made the same argument you're making about white South Africans, but instead about Jews; that Jews in nazi Germany should just have gone back to Israel/Palestine if they had it so bad.