First I would like to question the assumption in your question.

To start a company should a person be from IIT or NIT?

If so, then the following companies in India should not have been in existence:

Tata Group - Founded by Jamsetji Tata, not from IIT or NIT

Wipro Founded by M.H. Hasham Premji, not from IIT or NIT (not very sure, point out if it is wrong)

Sabeer Bhatia - Co-Founder of Hotmail, not from IIT or NIT

Kunal Shah - Co-Founder of FreeCharge, AGAIN not from IIT or NIT

I could go on however, the point is there is NO rule that states:

"Pre-requisite to start a company of your own is to have graduated from an IIT or NIT". This answers one part of your question.

In the details you also mention "Why did he not remain satisfied in his $120K job? Or what motivated him? That's fairly high for any standards in India". The answer to this is, he is the only one who can say definitely what motivated him or why he was not happy with the $120K job. However, I will try and answer it in general why people become entrepreneurs.

Opportunity: Some see a void in the market which is not being attended by existing companies in that area or they have the means to drastically alter the way business is done in that area. Thus, they see an opportunity and go for it.

Monotonous -ness: Some people consider a regular job very unexciting, boring or just not creative enough. This prompts people to do something exciting on their own.

Authority: This is a small share of people but, some people do not like the idea of answering to some one for their work. These kind of people will not fit in the dynamics of regular jobs.

Success-junkies: "Junkies" is a strong word however, I use it on a lighter note. Some people really like to gamble on their chances at success. They want to play the game and win BIG and they are ready to take that risk to achieve success. (How much of success will they taste is altogether a different topic)

Change the world:Some people become entrepreneurs because they truly believe they can and will change the way world perceives things.

Big Wad of Cash: Amount of money is very relative to each person. Very few people are content with the amount of money they make. This is a big reason/motivation for many to become entrepreneurs.

I will add more as and when I remember. Hope I have answered your question to satisfaction.

Sources:

Jamsetji Tata - wiki page.

Kunal Shah's LinkedIn page.

Sabeer Bhatia - wiki page.

Images - Google.