4. Quinton-van-Rooyen
In 1992, Quinton-van-Rooyen, 52, founded Trustco Group Holdings. It is now one of the largest diversified financial services groups in Southern Africa with interests in banking and finance, insurance, and asset management. Van-Rooyen owns more than a 20% stake in the company, which is dual-listed on the Namibia and Johannesburg Stock Exchange. His stake in Trustco alone is valued at more than $50 million.