Angola is a case study and I know it well.
It is a very rich country with substantial reserves of oil, diamonds, copper and bauxite. I think it is potentially the richest country in Africa. It is also very beautiful. When the Portuguese ruled it was a stable, peaceful place to live and visit.
Then came the revolution. It was 1975. The Portuguese were kicked out overnight and many left with just the clothes on their backs, such was the rush to get out. People lost everything, and I mean everything. Then followed 25 years of brutal civil war which has turned the country into a disease-ridden, primitive rock pile. It is only now just beginning to straighten itself out.
Is there something genetic about the blacks in Africa which causes them to want to destroy and pull down that which is beautiful just because the white man built it? Are they racists? Fools? Just naturally warlike? Whatever it is, they have it in spades.
Every country in sub-saharan Africa (except, maybe, for Botswana) is a prime example of “King Midas in reverse.” Angola, Congo and Zimbabwe (and soon, sadly South Africa) are stellar examples of this.
What you list are the outcomes of one frame of mind -- tribalism. They warred and killed each other off before the colonization and when the colonial controls were removed they reverted back to their fight for power. Before colonialism the various tribes made scant use of the natural resources there other than the triving centers of slavery and now that the evil europeans are gone once again making use of their natural resources is secondary to which tribe rules.