If people around the world just see Americans as Americans, what's the point of them identifying with a culture?

Sorry to ask, I don't want to seem ignorant but I really don't get it. Like, I saw a post on someone identifying as Norwegian-American and I thought of what another commenter said that most people don't do the stuff Americans do and how most people will see them as American. But I see many Americans strongly identify with a culture they were raised with. Is it still okay for them to do that? What's the point?