The other factor is gold savings. Most families have a large amount of it, and provide good insulation against inflation.
Pretty much bulk of India's middle class got rich in the post 1992 era, when the market were opened up making it easy to do business. The software riches came due to US money flowing in, the salaries were high. And most people got to travel abroad. And given foreign exchange factor most people made a killing till 2005. Back then it was easy to get US visas and work there. The dollar paid 35 rupees a piece and land prices in most Indian metros(especially Bangalore) were quite cheap. People who bought lands anywhere in peripheral Bangalore have seen their wealth increase by crazy factors.
The other factor is again opening up of mass private sector hiring, subsequent growth in economy and the stock market.
And lastly of course, corruption, nepotism and dowry market.