Being a resident of India, I have to agree. The biggest issue facing Indians right now is the shortage of natural resources, and the primary reason for that is the uncontrolled population growth. States with the highest population growth (Bihar, Meghalaya, Rajasthan.etc) remain as the poorest regions of India, while those with the lowest population growth (Goa, Sikkim, Karnataka.etc) have the best HDI ratings. There are tens of millions of migrants from the first category states who are working in the second group of states. The reason is very simple - their own states are overpopulated and can't provide jobs or facilities for these people.
I've spent a little bit of time in Karnataka. Over there on business, but I took an extra week or so to look around. Mainly I took a trip to Mysore (from Bangalore of course) and we deliberately drove one way on the back roads. There are a lot of people, but there was also a fair bit of area that did NOT have a lot of people.
People who travel only on the main routes inevitably get a misunderstanding of population density in ANY moderately populated country. Something which looks like city does NOT look like city if you walk 50 meters through someone's house. Houses tend to be along the road for fairly obvious reasons when one thinks about it.
Yes, I consider 1B people a bit higher than desirable for the area of the nation, but I do not see it as unworkable with good governance and a healthy society (which will almost by definition lower birth rates as a matter of people doing it voluntarily.) China has it much worse than India because of their dearth of arable lands and water. The REAL problem is that people who are in the 0.01% wealth/power-wise know that it will be increasingly difficult to maintain and grow their position with large populations who need to be mollified and controlled. So, they want the pleb population to be smaller and put a fair bit of their own resources into getting others to agree with their mindset (esp, 'global climate changes' and such tobacco pseudo-science crap.) That's my informal analysis. I think that you ought to at least consider this possibility in your analysis.