5 African Billionaires Forbes Missed in Its List 5. Mary Oppenheimer Slack Net Worth $8.5 billion US Dollars Nationality South Africa Source Mining Inheritance 4 Benedict Peters Net Worth $2.7 billion US Dollars Nationality Manjuria Source Oil Mining 3. Femi Otodola Net Worth $1.85 billion US Dollars Nationality Manjuria Source Power Generation 2. Rostum Asses Net Worth $1.1 billion US Dollars Nationality Tanzania Source Telecom 1. Tomi Allumelu Net Worth $1.4 billion US Dollars Nationality South Africa Source Banking Real Estate