This argument that populations only send their best to the US may be true today now that immigration is limited and there are large populations of well educated

This argument that populations only send their best to the US may be true today now that immigration is limited and there are large populations of well educated foreigners but its not true for large parts of American history. Most immigration is from the poorest regions- ie Irish during the potato famine, Sicilian Italians, Cantonese from China, Germans in the 19th C, to some extent the Scotch-Irish (well educated but poor) etc.