As the side comment, no they don't. China and India aren't half the world's population. And their share is falling.
Even if they were:
1. India is (partly) English speaking, so it doesn't fit the split.
2. If you exclude the English speaking world (let's say 1 billion people) and China + India (3 billion people), you're still left with almost 4 billion people. Out of which about 1 billion live in developed countries or are middle/upper class in developing countries. So that's a big market. Japan, the EU, Latin America, etc.
But a tiny part of your search-engine, social-network, app, or whatever is about the translations of the UI. The largest part is about how social constructs, ideals, workflows, and so forth fit. An Indian user might be able to read the screens on your app just fine, but might still be left out due to cultural issues.
In the EU this often becomes very clear when your startup "expands to Belgium" for example. It is not just about translating the app in Dutch and French; the way people interact, do business, communicate; the problems people have, the problems they dont have, and so forth are very different.
This is a pet-peeve of mine: we are all pushed in an American Template due to the prevalence of Silicon Valley "dictated" norms. When I was young, nudity on television in my country was normal. A local movie would have to have at least two naked tits. Today our media has become prude; no more tits on TV on prime-time; something that creeps onto us as "collatoral damage" of using primarily US media platforms.
Even if they were:
1. India is (partly) English speaking, so it doesn't fit the split.
2. If you exclude the English speaking world (let's say 1 billion people) and China + India (3 billion people), you're still left with almost 4 billion people. Out of which about 1 billion live in developed countries or are middle/upper class in developing countries. So that's a big market. Japan, the EU, Latin America, etc.