Most Nigerians believe that once they get to America they will achieve their full potential. So they holdback in Nigeria not seeing the potential and expend trying to get to Yankee. 
When they get to America they realize that greenbacks don’t grow on trees. One wrong turn and you might find yourself on Skid Row.

So they give their full potential at the car wash on Crenshaw, at Burger King flipping burgers or trying to do that same odu they were doing in 84. @OgbeniAyotunde