This is an odd definition. Apparently India and China, with their 20% savings rates, are middle class. But the far richer US (savings rate ~ 0%) is lower class?

This is an odd definition. Apparently India and China, with their 20% savings rates, are middle class. But the far richer US (savings rate ~ 0%) is lower class? And if the poor Americans suddenly started behaving like responsible Indians, they would become middle class?