From my perspective, I've never been afraid of black men. I grew up in a place where I went to school with all manner of different races and I grew up in a home where cultural differences were celebrated. I started dating black boys when I was 13, it wasn't considered taboo or even really noteworthy.
As far as virility, that's not really a factor for me.. I'm childfree and pregnancy freaks me out, I have an IUD and use condoms with zero plans to be bred. I realize virile doesn't only refer to procreation but it's generally used as the masculine equivalent to fertile so I have the whole baby connotation with the word. In terms of strength and sexual prowess, I think a lot of people view black men as the epitome of those things, here especially, because they're contrasted against cucks who are the opposite. Don't mistake my meaning, black men are strong, absolutely, black people are strong because they've had to be - they've faced generations of adversities. But are black men inherently any more sexually capable than any other race of male? I have no idea.
I can't speak to the vengeance aspect since I'm not a black man but I feel like you don't maintain a relationship spanning years with someone you're just using as a revenge fuck. Pretty much all my relationships with black men are long-term, positive and healthy.
I also can't speak to the cuckhold aspect since I have no interest in it, but I think there's been a truckload of input from that perspective already.