What are the reasons due to that best Indian doctors and scientists are working in USA and don't want to come back to India and contribute in the growth of India?

Money and quality of life. Simple as that. They have much more respect(in certain terms yes) , money they earn there is multiple times and quality of life- good infrastructure, implemented rules and laws, lower population density is an advantage for which there is no substitute. Asking them to take a govt. job here would be asking them to sacrifice all that to work in a corrupt system where there is a huge dearth of resources and funding. Promotions, reservations and other headaches anyone would like to steer clear off. They are that capable to make better off with their lives. Disillusionment with the system is what makes people from the top institutes shift to other countries. When you see corruption, cheats and bad policies every day you become fed up off it. Thats why certain people choose to settle abroad and contriBute to country through other ways. But yes- they chose to run away from the system rather than develop and clean it.

Opportunities for personal growth/ research are not as good as in US. Doctors need to get trained in US, UK, EU to attain skills to offer the best in healthcare. Once they are exposed to facilities, money and fixed working hours, many find it difficult to resist. Scientists get entangled in bureaucracy and nepotism.

Instance: I've a friend who was an avid follower of Discovery Channel & National Geographic from the age of 4 (at an age where a normal kid would watch Cartoon Network :-P) and would come up a new way for solving any household equipment issue. Currently interning in Japan, this guy is sure to become one hell of an engineer. But during his childhood all he would hear was "He's a brilliant kid, why does he waste his time building a working model of something people haven't heard of?" and my aunt would say "Thank God, he's constructive". His elder sister and I would think how what a great mind he has and people just keep thrashing him all the time, when will these guys have some sense. Reasons of NOT staying in India: 1. No support from Government- Funds, opportunities and policies keep Indians frustrated about the scope of work they can do. 2. Uncertainty- If you're not a part of Indian Government, then you are going to have TROUBLE. An average time for private company to start up here takes more than 6 weeks and by the time you want to develop your ideas, you will feel that you have done the biggest mistake one could EVER do. 3. Recognition- You are set to have your due in a more transparent country like USA rather than red-taped economy like India. 4. People donot consider Researcher as a Profession- Now, this may sound stupid and insane but general population does not even know what a researcher does in India unlike USA or any developed country. Even a Business Analyst needs to spend atleast 15 min explaining his Job profile (Only relevant Industry people get, the Greek you speak)