That is also because the inflation is at 6 - 9%, if they have a US average 2 - 4%, the loan principle will lose its value at 4% - 7% a year. That would straight away mean loss to banks.

Plus real estate is growing at a stellar rate, and probably will till the next 100 years. For India's rate of population and room for economic growth this is anything but inevitable. Heck there are even people who own 2-3 houses in the US. Doing this is Indian is hardly surprising.