> As you admit, “The US has its own problems”, so it is not successful

That's not at all what I was saying. I believe the US is wildly successful in integrating immigrants, since it is a nation of immigrants after all. Even the native population, which, despite what you said, was not entirely "killed". The indigenous population today owns a significant portion of land in the US and many tribes benefit significantly from using it or leasing it out (speaking from personal experience, the Agua Caliente and Apache tribes). Whether or not those tribes are "flourishing" is another fascinating story, but they certainly have the resources and potential.