I would argue that the US is experiencing a lot of problems, particularly the rise of Trumpism, because there's now a large contingent of immigrants (many not-s

I would argue that the US is experiencing a lot of problems, particularly the rise of Trumpism, because there's now a large contingent of immigrants (many not-so-recent) who don't speak English and have a very different culture. This has stoked a lot of xenophobia, and calls to "build the wall". China is almost all Mandarin. The SARs are really small exceptions and not like the rest of the country (by design). Japan's main problems are a low birthrate, and inefficient business processes (too many people spending too much time at work, but not actually being productive). But still, they have one of the world's leading economies. India is really a mess in a lot of ways, and as you point out, it isn't doing nearly as well as China economically even though it's started out from relatively the same point. There are counterpoints, however. 1) Switzerland. 4 languages, and the country is both economically super-prosperous (per capita) and safe, with the highest standard of living in the world. 2) Canada. 2 main languages (English, French), and standard of living at least as good as neighboring USA. I think the difference is that, in both these places, these countries basically started out with these major languages, and made very conscious decisions early on to accommodate these languages and regional cultures, and to be a place where they could all get along. But even this hasn't been perfect: Quebec has long had a separatist movement.