Since India has about one quarter of the planet’s entire population, it says something that tiny Britain has exceeded India until now.
Given how incredibly stifling and draining socialist policies are on countries economies, it’s a miracle the UK has that high, that long.
It took over overlordship of various Indian nations in the 1800s which is why from 1853 it overtook India economically.
Then from 1947 India implemented Socialism which kept it down -- THAT's the key reason why India is still poor. It dismantled socialism in 1991 and has been growing steadily and rapidly since then
So the answer to your question is that socialism sucks -- it kept India down and it stagnated the UK from '47 onwards (and still does). Why did Obama want to implement a failed policy in the USA?