Harsh geography? They have some of the most fertile and crop friendly climate in the world - why do you think they have such lush jungles? Africa is one of the most mineral and resource rich land masses in the world.
Colonialism? There hasn't been a real colony in Africa for well over 50 years. As for exploiting and expropriating 'riches' there have been repeated studies that show the maintenacne of colonies were a net loss for the colonialists. Several African countries were left operating very well when the colonialists left (South Africa, anyone?) - corruption along with socialist and communist governments drove out anyone who stayed to try and help in a transition and the continent is a basket case again. As for the 'artificially' imposed boundaries between tribes that hate each other - nothing stopped the natives from re-arranging the boundaries OR GETTING ALONG with each other. However, it is far easier to continue to hate, murder and kill each other and then blame Westerners as economic exploiters and claim reparations!
Finally, misdirected and open-handed 'aid' to Africa mitigates against the development of any indigenous 'industry' free clothing donations decimate local economics for raising and processing cotton into clothing. Free food - frustrates incentives for a farming economy.
My arguement is that is combination of things.
Something that happens 50 years ago can very much affect the way the world works.
In my opinion there are 4 factors:
Harsh Geography - Having been to Afirca I can tell you I would rather set up a country anywherer but there. It is rife with disease. This is the place that Ebola and Aids came from! Malaria and Typhoid are rampant.
Corrupt Leaders - This is a given.
The legacy of Colonialism - They were ruled for centuries then all of sudden left to their own devices - BAD IDEA!
Western States either profitting or ineptly helping.
Companies support corrupt leaders. Look at Nigeria. They make Billions a year in bribes alone and not one penny goes to the public, and I eman literally not one penny.
Comapnies support the leaders, the leaders support the companies.