The only problem I have seen mentioned that results directly from income diversity is envy. No one says they are envious, but they worry that others are. I can't bring myself to feel bad for people if their biggest problem is that they are not the richest folks in town. As you say, America's poor do well compared to people in most countries, and they are also better off than America's poor in the past. I don't see why it is "sad" to welcome the fact that American poor have a better standard of living than those in Nigeria or Pakistan. Thought experiment: Imagine that Carlos Slim (net worth: US$70 billion) moves from Mexico to the United States. Imagine, if you can, that he is able to get a working visa and then becomes a citizen. Obviously, this will result in reduced wealth diversity in Mexico and increased wealth diversity in the United States. Do you argue that this change would be good for Mexico and bad for the United States? I asked a similar question here but so far got no reply.there's something wrong
I am one of the silver-tongued apologists for the gap that humanodon mentions. I don't understand what is wrong.