Why is Africa still poor after all these years?

1) "Africa" is not a "nation". Africa is a continental landmass, that is home to many 'nations'.
In fact, there is more genetically diverse populations in Africa alone, than there is in the whole rest of the world!

2) Most of these problems stem from overpopulation, coupled with, and partially caused by being situated where the world's geomagnetic field is weakest (although this geomagnetic 'hole' is currently gradually migrating westward, across the Atlantic ocean, towards South America.