Singha wrote:what were the reasons why Hindus chose to remain behind in TSP even as news of the bloodbath during 1947 was spreading?
were they too poor to move or were too rich to leave it all behind?
Apart from extremely marginal numbers who stayed due to idiosyncratic reasons, the only significant number of Hindus who stayed were in Sindh. Tharparkar district had a Hindu majority but went to Pakistan. It was an extremely backward and impoverished district (still is) in very harsh terrain. For many of these folks, whose economic linkages to even the rest of Sindh were flimsy, partition would have passed without their even knowing. Since there was no significant immigration there (there was nothing to immigrate to!), there wasn't the displacing one saw in Punjab and other places. People might have felt some comfort in numbers, even if that view was short sighted.
The other set of Hindus who stayed behind were those in some of the urban areas of Sindh. They had again been a majority in many of the cities (Karachi, Hyderabad) and had some false security. These were well off and hence were able to fend for themselves better, both in the initial period and to some extent even today.
So in a sense, you characterization (only the poorest and richest stayed behind) is correct, but only in the case of Sindh. Even there, migration happened albeit slowly, of the urban rich. Only very small numbers were left behind by the time of the 1965 war (until when migration continued), other than the numbers in Tharparkar of course. In Punjab and NWFP, there was a mass scale and sudden cleansing of everybody, rich and poor. In Balochistan, there was some initial feeling of security before the province was annexed forcibly by Pakistan, but afterwards, this vanished quickly. The numbers were very small to begin with. In Bengal, there continued to be significant Hindus even in the 1951 census, but there was a gradual reduction of the Hindu percentage, both due to migration and due to differential birth rates. It has not stabilized till date.