'I'm Frugal': This 30-Year-Old Billionaire Says Life 'Hasn't Really Changed That Much' After Making Billions. Here's Where She Spends Money. The world’s youngest female billionaire, Lucy Guo, made her fortune from a startup she co-founded called Scale AI. Previous Article Is AI Bringing You Closer to Your Customer — or Driving Them Away? Here Are 5 Steps to Bridge the Gap Next Article Most Entrepreneurs Are Getting YouTube Completely Wrong — Here's What Actually Works