Economic opportunities are significantly higher in Delhi and Mumbai allowing larger numbers to break away towards higher income levels. The affluence ratio, defined as

the ratio of millionaire households to low income households is in general significantly higher in these two cities.

Grant Road-Walkeshwar is the neighbourhood which is most skewed toward affluence. The ratio of millionaire households to those earning less than Rs 300,000 per annum here is 27. The other major neighbourhoods skewed towards affluence are –

The skewness is much lower in the other major cities of India, where the highest ratio is in Kilpauk (North) in Chennai (3.44).
Among the top 100 neighbourhoods (in terms of ratio of millionaires to households earning less than 300,000 pa), there are only 2 from Bangalore, 7 from Chennai, and 4 from Kolkata. On the other hand there are 37 from Delhi and 50 from Delhi.
Clearly, opportunities are significantly higher in Delhi and Mumbai allowing larger numbers to break away towards higher income levels.

Source: The City Skyline of India – Neighbourhood Series. This product is designed to help marketers and strategists dissect the cities of India at extremely granular levels. It divides the cities into neighbourhoods which are as small as a few square kms. Delhi, Mumbai, Bangalore, Kolkata and Chennai have been divided into 128, 99, 102, 141 and 155 neighbourhoods respectively.