It just gets left to rot anyway.And more able to stay and rebuild their lands. If every able-bodied, fit man leaves, then who is going to rebuild that country? Or, does it just get left to rot, until China moves in and takes over?
I lived in several sub Saharan countries in the 70’s. Zambia, Zaire, Uganda to name a few. They were shiteholes then and shiteholes they remain 40 years later. So hanging around hoping for/working towards improvement will be a long wait whilst your family subsist in a dollar a day. Best up sticks and move to the land of milk and honey. It can’t be any worse.
If western countries invested in these places properly the Chinese wouldn’t get a look in. That we keep cutting foreign aid and assistance is precisely why these hordes of immigrants are on the way ( and if you think it’s bad now, just hang on 10 years) and why the a Chinese are moving in so rapidly.