It's just in-group preference. Robert Putnam was not the only researcher to find that ethnic homogeneity leads to higher-trust societies with more cohesion. One just has to look at racially mixed countries like Brazil or ethnically and religiously mixed areas like the Middle East to get a load of the devastating effects of long-term diversity.
Race is an extended family. When you travel to a country where your ancestors come from, you notice that people there resemble you in physical and behavioral ways. That's possible because we share DNA.
As we are more comfortable with people of our origin, we would not want that people to disappear. So, what would we do to prevent such a horrible thing from happening? Become preservationists or nationalists.
Part of being an incel is having to compete with other races of men that are conquering our young women. So, why would we want them in our countries? Why would we want Jews in the West if they are responsible for radical feminism and mass immigration? Tinder was invented by a Jew named Sean Rad, as a matter of fact. The same tribe behind race-mixing. Why would we support that?
What happens is that because some ethnics are resentful for not being White, they want to prohibit Whites from having a racial consciousness. However, that lack of consciousness is killing our race and civilization, so we have to fight back. And trust me: even though I'm an incel, I'd rather live in a first world country than a third world nightmare.
