I don't think your friend is going to change without a random event happening to him that puts him in a precarious position. He's saying it's better to be a homeless person in NYC than any historical wealthy person or any ancient sumerian king. That's a brutal misunderstanding of what it's like being homeless. No homeless person would ever think "man this sucks but at least I'm not Emperor Shenzhong and living in a palace with a thousand servants."

Your friend is stuck thinking he lives in paradise, he disregards what poor people now think and feel, and he lives in a bubble.