I live with 500-700Eur/month since multiple years and I live a life of luxury compared to most others (and with that I mean my friends from Western Europe) and that includes traveling. So that'd be about 25-30 years which I'd call enough for retirement.
Don't forget: it's not like you'll never work again...honestly who wants to not work the next 30 years? there will always be some small jobs or part time projects which will produce some sort of income, even if not monetary
I am not even that frugal, I live reasonable, but I spend lot of money on sport equipment, obviously I am not driving a Maserati or live in a Villa with pool, but neither do I live like a monk or live in hostel dorms, my luxury is that a) I don't have to work b) if I work I do what I enjoy and as many hours as I wish (which is probably the best of it) c) I can go wherever I want whenever I want.
Ok, but you're not really spilling the beans here. You could be living at your parent's place in Western Europe. Or perhaps you're living in rural India. That's what I'm wondering about.