It's no surprise that Kim Kardashian is worth billions of dollars, with her reality show, various product lines and business ventures raking in the cash. However, her former step-parent Caitlyn Jenner, 72, has revealed Kim's secret to success - and it's apparently pinching the pennies. Caitlyn, who discusses the family's rise to fame in Sky's new documentary House of Kardashian, revealed that Kim "calculated from the beginning" how to become a celebrity and has always had an impressive work ethic.