Why was it that technological advancements made in Africa were not enough to propel Africa's economy upwards?

Brazzaville and kinshasha, luanda,librevilleand and monrovia.

Africans learned what the europeans wanted them to learn. instead of learning about african history and current information that could and would them they learned solely what europe wanted them to. and not everyone received the same education, some received better and others none.