Probably the three main expat groups worldwide that prosper in host nations are:
Arab Christians
Sephardic Jews
Ethnic Chinese
They run commerce in the Caribbean basin for all intensive purposes
I would have thought Ashkenazi Jews would have been your choice, but that will do as well. There are lots of others of course - Parsis, non-Muslim Indians in general, Armenians, Koreans, Japanese, etc., as well as most European groups, lets not forget.
The fact that there are so many of these groups, and that they are so ethnically and culturally diverse, leads me to think that it should be relatively easy to find a common success factor, and I am tending to the possibility of some humble, simople cultural trait, perhaps some parental behavior in early childhood.
Being a merchant does not need strength, health, and endurance as much as it needs being smart. A smart merchant could afford to feed many children, while a stupid merchant would get cheated and be unable to support a family. Over time, ethnic groups that were primarily in a "merchant" niche would select for intelligence