Who is going to organise 700 million people into so many sectors?
India has an army strength of 900,000. Of those 900,000 at most there would be 360,000 infantry soldiers whereas the others would be into duties like engineering, communications, radar, armor, artillery, education, mechanics, cooks, cleaners, teachers, lawyers and other desk jobs.
Cyber sector and operating drones are high-tech departments which will need highly qualified people and also TRAINED people. Weapons production also needs people who are qualified and know what they are doing. It is not WW2 where people can mass in a factory.
If building up an army was so easy then India would have fielded a 10 million strong army by now.