There are well-off Somalis in the west as well. Hell, you guys have just been in these places for 1-2 generations and somehow you're producing congress members, officials at The Hague, Mayors and so forth. Now, perhaps there is indeed a higher incidence of wealthy types in the African and Asian diasporas and that's mostly due to a form of selection.
There's not really any welfare system in most of Africa and Asia and outside of countries like Kenya and Ethiopia where we can get citizenship you're pretty much gonna be deported if you don't have a job or own a business so the Somalis in these countries tend to either be hardworking laborers, professionals or well-off business folks whereas in the west many are there as refugees and with refugees you're not always getting the cream of the crop, of course. And lots are tahriibees looking for cayr so you're just gonna be selecting for a different sort of person altogether there as well. Simple.