The geography of South Korea seems to help. Typhoons collect into snow on the rocky mountains, that melt throughout the year into clearly defined rivers without much penetration into soil. There is an ecological buffer that some parts of India don't have to maintain levels of drinking water throughout the year.

Yes, but they are still 50M overall. They maintain that quality of life by supplying the rest of the world with much of its cars, electronics, phones, and other crap (including pop music and movies). You can't do it at a size 30 times as large, or you'd need an entire solar system as your market.

You're implying that humanity net overall has a fixed output and the only way a country can do well for itself is at the expense of others. Technological, infrastructure and agricultural improvements, and more efficient use of resources make the whole "pie" bigger for everyone, and don't require being a top 10 economy relying on a resource rich 3rd world.