Indians leave India because it is overcrowded with 14 times higher population density than USA. History is replete with people exploring other places for better life. Why do you think Britain established colonies all over the world? It was said Sun never set on British empire. So did French, Dutch, Portuguese and Spaniards. Why did they explore other countries? Were their countries shit holes? Nope. It is human trait to seek better life. Columbus was searching a sea route to India because India had the goods (spices, gold, diamonds etc) which were valuable in his country.
Sure, but there could be different reasons. Colonial expansion for commodities is a legitimate reason. So is escaping a crowded, dysfunctional place with poor infrastructure.