Engineers get a much higher paying job. Computer engineers (both hardware and software) get paid 10-20 times as much as other professions. MBAs get more. Note that even students who do Mechanical & Civil engineering try to get software jobs. That's where institutes like Aptech and NIIT come in (they're now global franchises, but they started as tiny training institutes in an Indian city). I once met an auto-rickshaw driver who had a Bachelor's degree in science. He started driving the rickshaw because 2 years after graduating he couldn't get a job. If he'd done engineering, his college (or training institute) would have placed him somewhere.

When I graduated high school, and was in line to submit my college application, I heard a bunch of people mention that they'd applied for engineering and medicine and would take whatever they got.

Another reason, specific to guys is that it increases their chances of getting a bride from a "good" family, and also the potential dowry he could get. Software jobs tend to take you abroad more often than other jobs, and, believe it or not, there are some communities in India that will raise dowry prices based on the number of US immigration stamps you have on your passport. Yeah, officially dowry doesn't exist.

Lastly, some people study engineering simply because they're really good at it. I've encountered hundreds of people who really had the aptitude to be engineers.

Disclaimer: I'm Indian but I studied Physics, Chemistry and Mathematics. No one would give me a job after I graduated even when I cleared all interviews and written tests.

If someone starts earning Rs 25000 (~$550) per month after college, generally it is almost equal or close to what most middle-class parents earn themselves.

Being an engineer always provided a possibility of getting a decent job, but the trend was accentuated after the advent of IT Services companies thriving on outsourced work. This in conjunction with a large number of private engineering colleges setup in the 1990's, meant engineering became an easy ticket to getting a decent paying job. And at the end of the day, money matters especially in a poor country. (Btw I'm an Indian living near Delhi, before someone thinks I'm just trying to bash the country.)

On the positive side, things are changing for better. Post economic liberalization in 1991, there are plenty more opportunities for young (& old) people to earn a good living. Overall, economic development coupled with information revolution are paving the way for this and the future generations to take more risks and do what they want, rather than worry about basic necessities of the life.

I was around 10 in 1991, and I have literally seen things/attitudes change in front of my eyes. (May be everyone thinks the same ..). I am very hopeful and optimistic that more people would now start getting in to different things/professions.

risk free 'Exit' path to the big world. How many Phds in history are needed vs CS people? What would Indian history major do to pay the bills after she graduates?

In US a history or philosophy major can survive, and even run big companies (like LinkedIn) or go for a law school

"That just begs another why. Any ideas?"

Money. Respect in society.