Elon Musk vs. Amancio Ortega

Musk, who says he's worried about population collapse, has nine children with three women, including triplets and two sets of twins. As a kid in South Africa, Musk taught himself to code; he sold his first game, Blastar, for about $500.

Ortega first began his career manufacturing textiles through a small family company in 1963. He owns a 10% stake in Spanish telecoms firm Telxius and 5% of publicly traded natural gas grid operator Enag's.