African business moguls often face accusations that their fortunes were illegitimately earned, including with extra-legal help from political patrons.
The apparently rising number of ultra-rich Africans has come amid broader economic growth on the continent, which has seen an average of 5% GDP expansion since 2010.
But economic growth has not kept up with a rising population.
“There are more than twice as many extremely poor people living in sub-Saharan Africa today [414-million] than there were three decades ago [205-million],” the World Bank said in April.
It is the only region where “the number of poor people individuals has risen steadily and dramatically”, over the last 30 years, the bank said.