[A2A] This question contains an inherent assumption that "Entrepreneurship is better than being a professor at IIT". I don't know how opening and running a company is better than any other profession. Why is it better than being a bank employee or a farmer or a coaching teacher or an IIT professor for that matter? If you are asking this question to us, why don't you ask Ambani, why doesn't he go and teach in IITs? He surely has free time. Why don't you ask Dhoni to open a business? He has a lot of free time. They only play about 100 days a year. He is free for 250 days in a year.
It is our choice to teach in IIT. Why should I have to do more than one job? Why should I spend all my free time working on my startup? I don't want to do that. Why should I have to deal with the headache of managing employees? Dealing with students is enough. If one is taking a job as a professor (as a conscious choice), you can say that he is not that interested in money. People open companies to make money, whatever politically correct reason they might give you like: "I want to help India. I want to help people of India." So when money doesn't interest you, why will you open a company?
Moreover, some people are not built for business. They don't have the temperament to deal with the headaches of running a business. I, for one, don't think have it in me to run a business.
Now, there are some professors in IIT Delhi who have successful startups. So, there are some IIT professors who are obviously doing it because they are interested in it, but that does not make them better or worse than others who are not doing it. It is the personal choice of professors to do what they like to do.