It's not that simple.  Wealth does not equal immigrants.  Finland ranks high on per capita and it's arguably more developed than Britain, Canada or America.  Only countries who rank higher than Finland are the Scandinavian ones (and maybe like Qatar and that sort of stuff).  There are no cities in North America or Britain that come anywhere close to the beauty of Helsinki or Turku.

Finland is 98% European (when you add together Finn, Swedes, Russians, Estonians and Sami) and yet the foreign hordes are not pouring in (and the locals are protesting heavily the few 'refugees' that come in).

Greece isn't that much more developed or wealthier than most of the Eastern European states and yet Greece has a million African / Arab ******s pouring in.

Even Belarus is more developed and wealthier than anything in Africa but if Africans tried migrating there by the million, the Belarus Armed Forces would declare an hostile invasion and would start putting heads on pikes.  ;D