So people can never be happy if inequality exists? Sounds like an unsolvable problem. No matter how good everything gets, people will still be unhappy because someone else seemingly has it better. 1000 years from now:
"Poor person: Sure, I own a 7000 sq ft mansion with an electric drone that can fly me around everywhere and my life expectancy is 105 and my standard of living is an order of magnitude better than the richest people living in 20XX, but Elon Musk VII's life expectancy is 120 and he owns an entire planet with a space fleet, my life sucks, the universe is so unfair."