Economics is a zero-sum-game; if they lifted everyone in China out of poverty, then poverty is exported to other countries or the nature paid all the costs.
Edit:
Nature is a silent sufferer in the economics. It acted as cushion to our misadventures, a-bomb(wars), oil-spills, co2 & other gases, industrial wastes, nuclear wastes.
For a person to become rich, they have to earn profit dishonestly; if profit is shared equally nobody is richer. Somebody is getting short end of the stick to make someone else richer.
If everyone is self-sufficient through out their lives, then technically there is enough to go around. Otherwise, one who holds the resource in high demand won't share it fairly.
Simply put : Income disparity will thrive in resource hungry society where resources are held by few members. Even in self-sufficiency, if population grows then nature has to pay the price. Resources are finite for all kinds of life on earth. If one thrives some other suffers.
Anyway, now it's downvoted; wasted my time wording it.