Actually, no it's not for everyone. My wife and I are swingers, so we've met our fair share of people into bbc/cuckolding/hotwifing, and practically all of them like this fetish from a completely different perspective. Most of them are somewhat right winged people who do it from more of a 'beastiality' perspective. They don't actually think that black people are better, they just use black people as big dicked sex beasts for their own lust. The appeal of seeing your wife let a bbc fuck her, is very similar to seeing her let a dog fuck her. The act of her letting a primitive beast fuck her is what makes her so naughty and slutty. Of course, most couples don't literally call it beastiality, but this is essentially what it boils down to.
The people that actually get off on bnwo/white extinction/etc stuff is a relatively very small group of single white men on the internet who have very severe mental issues, usually largely revolving around deep unhappiness and inferiority complexes, who, instead of taking action to actually improve themselves and find happiness in life, use inferiority fetishes to find temporary pleasure in the form of "seeking comfort in defeat". The worst irony of this fetish is that women think it's absolutely disgusting. The only women that are actually into humiliating men are either payed for it, or deeply, deeply traumatized themselves. 99,99999% of all women think this humiliation stuff is an EXTREME turn off.