Popstar/businesswoman Rihanna has dethroned Kylie Jenner as the youngest self-made female billionaire in the US, according to the latest Forbes rich list. The 34yo has amassed an estimated net worth of US$1.4 billion (A$2.1 billion) thanks to her Fenty Beauty cosmetics line and lingerie brand Savage x Fenty, on top of her music earnings, of course… The next youngest person to be named is 41yo Kim Kardashian, with an estimated net worth of US$1.8 billion from her beauty company KKW Beauty and shapewear line Skims. America’s richest self-made woman is Diane Hendricks, the co-founder and chairman of ABC Supply. She’s built one of the largest wholesale distributors of roofing, siding and windows in America. Forget the fashion and beauty game – she’s worth US$12.2 billion. Now we’re talkin’…