This graph has nothing to do with what we are talking about. You are pointing out a graph of those with indian backgrounds in the USA and how well they are doing. Most of these Indians are born in the USA, educated in the USA, and have grown up there for multiple generations now.
The Indian visitors that go to Europe and USA are hardworking, middle / upper class indians. Many have been there for a few generations now - hindus and Sikhs.
The vast majority of Indians you see in Thailand are the bottom of the barrel, Budget travellers, sex tourists, horrific hygene, public urinatung, littering everywhere and the most horrific set of tourists you can find.
So you pointing out a graph of how well Indians are doing in America is pointless. They are Americans (with an indian background).
For the middle class Indian and Chinese, there dreams are to travel to Europe or the USA. None of them have aspirations to travel to Thailand. So you end up with budget travellers who will go whichever country will let them in, often on package deals, with everything paid for.