That’s a shit take.
Discussion
Would it still be a shit take to say that Japan is better off being Japanese? Or that it's better for Israel to be Jewish?
Homogeneous societies always work better. Everybody likes and trusts each other. The rules are easier to understand. People are friendlier. Education is better. There's less violence. People take pride in their communities. Everybody's "on the same page", cooperating. Kids can run around and be kids and their parents don't have to worry.
If you want to live in a homogeneous society I’m sure you can find one where you’re happier. The United States has been multicultural since the beginning. The fact that the founders, all of them immigrants or descendants of immigrants, didn’t think through the consequences of mass-importing slaves and realize that at some point their descendants would live free in the country where they were born is not the fault of anyone alive today, but we can never become a country of a single ethnic group because we never were to begin with.