> why some cultures are so much more economically successful than others
They're not. You're falling prey to selection bias. The Indians, Chinese, Bengalis, Nigerians who have chosen to go abroad are unique and special. They're the ones who take this courageous initiative to go into a land of unknown, likely other Chinese who are not travelling abroad - if they would, they probably wouldn't do as well.
I suppose the other part can be explained by culture. I'm a brown guy who came to America sometime ago, my family relatives are right now basically all priming their kids to become doctors. They are so committed to the idea that their kids are going to become doctors that I would bet a good amount of money that the kids will get good MCAT stores, will get residency, and perhaps even open their own clinics (they know this is where the money is, and they let their kids know this too).
The path of lifee I think is more conservatively and clearly defined in India than in America or other Western societies. In America, if your son wants to be an artist, a painter, a musician, you tell him to try his best. Indeed it is socially acceptable both by families and our society for a person to aspire to be anyone he wants to be, to do anything he or she wants to do. In contrast, the strongly knitted social cohesion and solidarity of places like India and Bangladesh impose a certain structure and path: you go to school -- you try really hard, you respect the hell out of your teacher, you go to college, you get married, and you try your darndest to provide as much as you can for your wife and kid. And that is not done by playing with high-risk games -- it is done by going the way that is known and suggested by community leaders, friends, families.
I don't think I've answered your question very satisfactorily or completely, the best I can say is it's the culture that's responsible for this. And I'm totally not happy right now with mainstream culture of America (especially the one lead by corp: misogyny is rampant (have you read the shit Eminem says in interviews? Why is Chris Brown still so celebrated?), math/science aptitude is equated to unattractive geekiness, etc. etc.
They're not. You're falling prey to selection bias. The Indians, Chinese, Bengalis, Nigerians who have chosen to go abroad are unique and special. They're the ones who take this courageous initiative to go into a land of unknown, likely other Chinese who are not travelling abroad - if they would, they probably wouldn't do as well.