Their government would be my guess. I don't think they even had one for awhile.

lorne13 name me a modern African country that is under Western power. I'm giddy with excitement to hear your answer. Besides what happened centuries ago doesn't make one jot of difference. Britain looted India for 2 centuries. Yet look at them now. China was repeatedly invaded by Mongols and Japanese yet look at them now. Blaming every evil on the planet on Whites is a fools errand.

Corrupted governments, tribal conflicts that have often turned into civil wars, social and political instability...anything that investors try to avoid.

global warming.

The exploitation of thr resources by foreign forces..why gaddagi was killed because he did not want to trade oil in dollars

Our world works on potential difference.. comparison.. so we need poor to show off as rich.
Even they did some studies showing that African humans got low IQ or caliber for worldly matters..( seems a foreign authority)
Sometimes it looks like Africa has been used as place for experiments too...and the violence kept it under developed

@kasthuri, check Tenente's answer, I heard about those colonial agreements still in effect till these days.

government corruption

I think Africans are too preoccupied with machine guns and ethnic cleansing. Very limited thinkers. That's the picture I get- at least of sub-Saharan Africa. I wouldn't invest in people like that.

interesting question..

Go research it.

Again, corrupted and selfish officials.

westerners been looting it for centuries

Inferior culture.

locked into colonial era agreements with international "investors" that ruined africas future