PEOPLE.comKylie Jenner's Cosmetics Empire Is Worth $900 Million - and She Hasn't Even Turned 21 YetPEOPLE.comKylie Jenner may be the baby of the Kardashian-Jenner family, but she's on the road to becoming one of the most successful (and youngest!) female entrepreneurs in the country. At just 20 years old (she turns 21 on Aug.