Yet people built it and made it that way.
Nothing is static people csn change anything
These people need to do that in their own countries.
That's false. By definition none would have come if there wasn't opportunity. You don't need to be a geography student to see that it wasn't just irreligious opportunity.
In America we built companies art and music out of our garages just for the love of it... not because "that's where the compensation was."
Because if not, then investments to Nigeria past $x will grant it the upperhand since all that money can get you another doctor and more.