How do you stop the better people from moving out of India (and/or to another firm) once they have your work exp on their resume?

Q: How do you stop anyone from moving to a better company or better-paying role?

A: You don't. Unless there isn't a better company or better-paying role.

If a person is motivated to move out of the country altogether it's got nothing to do with you and there's nothing you can do.

With higher salaries (is happening) and better quality of life (I do not know, do not life there). Within company obviously quality of the culture matters there.

However considering how things are worldwide right now, I think that trend stops soonish.