Kylie Cosmetics' 20-year-old Founder Kylie Jenner, whose net worth is $900 million, may beat 34-year-old Facebook CEO Mark Zuckerberg as the world's youngest self-made billionaire. Kylie has featured on Forbes' America's richest self-made women list for the first time. Zuckerberg, who became the world's youngest billionaire at 23, is currently the world's 5th richest with $76.8 billion wealth.