How is it that white people are so dominant in South Africa?

I don't wish to appear racist or anything like that, but it is whites who built roads and cities and infrastructure and so forth. There are some good examples of black African governance however, such as Ghana, Botswana, and I think Tunisia. Even though it's north of the Sahara. Ultimately now, white South Africans are falling into the poverty trap, like everyone else and don't have much hope.