It's not nostalgia. I was raised away from my homeland.
I can go into the ethnic aisle of my local grocery store and stand in the part that corresponds to my ethnicity. I find there better versions of the local foods. Better for me, at any rate. Tastier versions, more nutritious versions. It's just more comfortable all 360 degrees around.
It's in the genes.
The reason these ethnic foods are the way they are is because everyone in my homeland has preferences that are simply more similar to mine than the folk who live around where I was raised. We don't like the foods because that's our culture, our food culture is like that because we like those foods. The locals don't even realize these things can be preferred in many cases. If you'll pardon the gamerism, there are ethnic food mechanics that the locals simply don't play with.
The same thing happens with music. Everyone agrees that this composer and that composer are the best. I prefer the one whose name sounds like mine. His taste in music was closer to mine than the "best" composers were, and closer enough that it overcomes the skill deficit. Perhaps the notes are arranged less artfully, but it speaks to my soul in a way the "better" composers didn't even care to attempt. The fact he's obscure is a bonus as far as I'm concerned. Allegedly we can all interbreed but as far as art goes foreigners might as well come from a different planet, never mind a different species.
Food and music are obvious. Customs are less obvious, but it works the same way. The customs get that way because they play to the race's desires and buffer against their vices. It does so on so many points that you get a diffraction effect: telling the difference between similar cultures is trivial. And it matters.
I moved from somewhere that speaks my language to somewhere else that also speaks my language. I came by it honestly: my parents did the same. However, unlike them I wisely chose to move somewhere that is further to the right, very deliberately so. I got culture shock. Not a lot, to be sure, but enough. There will perhaps always be that tiny fraction of a second delay while I remember that the locals don't go in my default childhood category of "locals." (Praise be.)
I am a mutt. Certainly I have an obvious primary race, but it's also obvious that my ancestors really got around. I seem to have the full trifecta: negroid, caucasoid, and mongoloid. Luckily it's far enough in the past that I'm beyond the hybrid degeneration trough, but it's not so far in the past that I can't tell I'm miscegenated. Result: I don't quite fit into any culture anywhere. My virtues and vices don't quite slot into any culture anywhere, because there's no racial ghetto which is miscegenated quite the same way I am. The most obvious is my combination of adaptations to both northern climates and southern ones. Nowhere on Earth has the combination of sunlight intensity and weather that works for me. Technology can fix this, but technological solutions to biological problems are always clumsy. If nothing else it's an unnecessary expense that true locals don't have to spend on.
"White" is not a race. "Black" is not a race. (Even if they were, I would be neither.) There is no white culture or white foods or white music. There are no white police or white laws or white history. Maybe there's a white religion, but it sucks so who cares.
If you move from one "white" country to another "white" country, thinking, "They're both white it will be fine," you will be unpleasantly surprised. At best everything will be a little bit off. More likely at least one or two things will be flagrantly counter to your immutable preferences. It will never quite work out. It will always be at least a little bit of a struggle - in retrospect, a fully unnecessary struggle.
Folk in England can tell which part of England you're from by how you speak. The Japanese archipelago makes it easy enough even foreigners can do it. Do you suppose it's only language? "Race is skin deep" lol. It's not just "white" that isn't a race. Whether "English" is a race is debatable. Nihongo have to go to a lot of trouble to make "Japanese" a race. They do, because conformity, but nevertheless. Even if you move from one part of Germany to another, you can expect problems to arise. You will have to adapt. It will, perhaps, never quite come naturally.
At best, "race" doesn't matter and nobody should care. The relevant distinctions are more like clans or clades, and occasionally individual villages.
You don't need to move to the city to find a job. (Amish again.) What you need to do is find a way to move the job to your village. If you're feeling lazy I suppose you can go, but remember to take your entire village with you. Don't move alone to the city, move with everyone to the city and settle in next to each other as a unit. Try not to be culturally outclassed by Gypsies of all people.
The good kind of cosmopolitan only visits. Some folk are smart enough to entirely master their local culture. They get bored and want to challenge themselves. The obvious next step is learning about a foreign culture.
You're supposed to come home though, pervert. Try to fit in, to pass, but don't actually go native. The idea is that it's hard to think of everything yourself, and this applies to cultures as well. While mainly foreigners do things in a way that's wrong for you, occasionally they do things that are more right for you than your own native customs. The cosmopolitans are supposed to find these things and bring the back.
It's important so I'ma say it twice: bring them back. Don't stay in the foreign land. If you feel the need to stay you're probably a loser; develop humility, go home, and honourably face your failure. Offer not valid if your homeland has committed cultural self-mutilation. If your culture has become a shitheap, it's fine to be a refugee in someone else's. Probably best to explicitly work on reverting the harm, though. Don't just laze around bewailing your misfortune. Not that I'm going to hold my breath while waiting for repairs to start...
It's unambiguously better for everyone to live around those who are like yourself.