Why is South Africa the most economically unequal country and also very unstable?

I know about apartheid, but it’s been quite a while. Why is South Africa still so economically unequal today? By Gini coefficient, it is considered the most unequal country. On Google Maps, you can see ghettos right next to wealthy gated communities. The top 10% controls 90% of the country’s wealth. On average, a white household is roughly 20–25 times richer than a black household, according to statistics.