Kylie Jenner — "Billionaire" at 21 (Debated)

Forbes declared Jenner the youngest "self-made" billionaire in 2019 at age 21. Then Forbes revoked the title in 2020, accusing her team of inflating revenue figures. The Coty acquisition valued Kylie Cosmetics at $1.2 billion (she sold 51% for $600 million). Whether she was ever technically a billionaire is debated — but the $600 million exit before age 23 with a team of seven employees is indisputable. She built a beauty empire from Instagram lip kits that sold out in 30 seconds. The "self-made" debate will outlive us all, but the $600 million check already cleared.