And, all things considered, India's hardly done "terribly".
It's a remarkable achievement to maintain a united, democratic, mostly peaceful nation for 70 years straight (and counting). Most former colonies collapsed into destructive civil war, then military rule, within decades of independence. India has so far avoided that fate. Heck, most developed European countries have barely managed to avoid it in the past century.
India has as much (probably more than) linguistic, cultural, ethnic and religious variety as the European continent, far lower levels of education, absurd amounts of competition for resources, education, and jobs due to population pressure. All of those things are potential triggers for conflict and civil war.
I can't comment about other countries that may or may not have lived up to their economic potential (Brazil, Argentina, Russia etc) because I know next to nothing about them. But India is doing terrifically well, considering the hand we were dealt.
The colonies that fell apart we're ones where there wasn't much organization and what organization existed was for resource extraction.
The Dominions were built for settlement, so they were sustainable states. India and other Asian colonies already had their own very established cultures and civilizations, and hence fared much better.
Pretty remarkable India hasn't exploded into separatism due to resource pressure, but I don't know how sustainable that is given that the population is still increasing
It's hard to compare India to any other country except for China. No other nation is of a comparable size. It's all well and good to say "well Japan, South Korea, Singapore did great after being devastated by war and depression and famine". Just like software, scale matters for national development.
Japan post-war still had the relative advantages of having been an advanced industrial nation pre-war, with all that that entails: educated population, knowledge of how to run industry and finance, culture of industrial entrepreneurship etc. Plus it got tons of help from the US getting back to its feet. Ditto for South Korea; US help to keep them from falling over to the Communists. Both nations are also relatively homogenous ethnically, religiously, and culturally.
Singapore is tiny: a city-state. It's half the population of metropolitan Mumbai and has 1/3rd higher GDP. If Mumbai was an independent city-state with immigration controls, we'd likely be talking about it as an up-and-coming Asian tiger.
I'm not downplaying any of these countries' achievements. They are tremendous and they've done very well for themselves. I'm just pointing out the context of their achievements and how that doesn't apply to India.
I think it's impossible to say India hasn't lived up to its full potential because we can't run history backward and forward like a simulation, change a thing here (eg. make India a liberal free-market economy in the 60s instead of a closed, socialist one) and see the difference. China is doing great now but they had to go through the Great Leap Forward and the Cultural Revolution on the way there. India is doing not-as-well but at least millions didn't die.
It's a remarkable achievement to maintain a united, democratic, mostly peaceful nation for 70 years straight (and counting). Most former colonies collapsed into destructive civil war, then military rule, within decades of independence. India has so far avoided that fate. Heck, most developed European countries have barely managed to avoid it in the past century.
India has as much (probably more than) linguistic, cultural, ethnic and religious variety as the European continent, far lower levels of education, absurd amounts of competition for resources, education, and jobs due to population pressure. All of those things are potential triggers for conflict and civil war.
I can't comment about other countries that may or may not have lived up to their economic potential (Brazil, Argentina, Russia etc) because I know next to nothing about them. But India is doing terrifically well, considering the hand we were dealt.