Cultural thing or…selection bias. The people who left were the ones with the personality and work ethic that leads to being successful.
Historically, people who have left China are from Guangdong and mostly the poor & uneducated people. So the Chinese people you see in the US, west, Singapore, Malaysia, Vietnam, etc. are mostly from Guangdong.
Read up on Chinese migration from Guangdong during the US gold rush and railways and why they left.
Eventually, Chinese people in nearly all countries rise to the top of the income/wealth chart. For example, the richest group of people in Vietnam, Philippines, Malaysia, Indonesia are all descendants of Guangdong people who migrated. In Indonesia for example, Chinese are 1-2% of the population but owns 70% of private wealth.
Fun fact, most Chinese people in China do not eat dim sum. Dim sum is a cuisine popularized by Guangdong (Guangzhou/Hong Kong area). There are also many regions in China that don't even eat rice. They eat bread or noodles mostly. Chinese image outside of China are heavily influenced by a small area in Guangdong due to immigration.
Small correction, a significant amount of Chinese migrants are from Fujian, which borders Guangdong. You can usually tell from the language spoken—Fujian descendants speak Hokkien while Guangdong descendants speak Cantonese, though it's not a hard rule with the regions being adjacent, of course.
In countries like Malaysia, it seems to be an even mix of both but in others like Philippines 90% are actually from Fujian.
That does not explain why other similar communities haven't done as well, even though more of their people have migrated.
Take the example of Britain, where they currently have a larger ethnic British Pakistani population than the British Indian population. Yet there are only 25% Indian households and 33% Chinese households in the bottom income quintile, while there are 44% Pakistani households and 49% Bangladeshi households in the same (White British is at 17%). On the other hand, Indians and Chinese are massively represented in the top income quintile at 20% and 28% of households (compared to White British at 21%). Only 7% of either Bangladeshi or Pakistani British come in the top income quintile, even underperforming the Other Asian category (who are 2x at 14%).
Isn’t it more likely that Pakistani folks in Britain are more likely to be first generation immigrants? You’d need to compare generationally to get apples to apples
Perhaps one could argue that Indian migrants tend to be educational and work migrants, while Pakistani migrants tend to be family reunification migrants. But that again points back to the cultural reasons behind certain communities doing well, based on what they prioritize.
The raw numbers don’t seem to address gp’s point. Indian migration started earlier than Pakistani migration, so you’d expect more second+ generation migrants among Indians.
Edit: sorry, I didn’t realise you meant migrant flows. That is relevant, though it would still be better to control for generation.
