Do successful countries tend to be more or less culturally diverse?

For decades the US has been the most successful country on earth and it is highly diverse

It's hard to say. I dont know much about American history but there were a lot of different cultures coming here after the industrial revolution when the American dream was still alive. I couldn't tell you about how diverse it was before that and the part diversity played in overtaking Britain as the world's strongest empire.

Now your "power" is based absolutely around military. You're a poor schoolyard bully with no dad, a stripper for a mother and no lunch money, so you have to go around taking lunch money from other, smaller and usually blacker nations.

diverse countries seem to be more successful, look at the UK, America, Canada, Sweden, And so forth

But look at Contries that are not diverse, The Phillipines, Africa, Mexico,