Wrong.
Distribution of income has jack shit to do with how successful a country is. I'm sure the wage scales in North Korea are as flat as hell, with the exception of a few in the ruling class.
It should be shriekingly obvious by looking at the United States and its economy, and then the nations with similar numbers to ours in that scale, that something is drastically wrong with how the GINI index is calculated. Unless you think more people would rather live in Iran, Russia, Pakistan, East Timor, Bosnia, Rwanda, or many other nations that got a "better grade" than the U.S. did.