Kylie Jenner has become the youngest self-made billionaire at the age of 21, according to Forbes, after using her Instagram influence to build a lucrative make-up empire.The make-up entrepreneur and reality television star has overtaken Mark Zuckerberg, who became the youngest self-made billionaire aged 23 in 2006.Ms Jenner, the half-sister of Kim Kardashian, has used her 128m followers on Instagram as a customer base, as many follow her for fashion and make-up tips.The entrepreneur owns 100 per cent of Kylie Cosmetics, the three-year-old beauty business that did an estimated $360 million in sales last year, and most of her sales are done online. Much of it is driven through social media.She has attributed her rise up the rich list to her vast and dedicated following, telling Forbes: “It’s the power of social media.“I had such a strong reach before I was able to start anything.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Recent sponsored posts show the young woman posing with vitamins promising glossy hair, and “detox” tea, which is said to give the user a flat stomach. Jenner was ranked at number 2,057 out of 2,153 on this year’s list. Of the total, 1,450 members are self-made.The number of billionaires in the world is decreasing, according to the list, with 2,153 billionaires on the 2019 list, down from 2,208 in 2018. The total combined net worth of this year’s billionaires is $8.7 trillion, down from $9.1 trillion in 2018.For the second year running, Amazon founder Jeff Bezos topped the list with a net worth of £131bn, with Bill Gates, who previously held the top position for a record amount of time, second with £96.5bn. Her first foray into the cosmetics industry was through selling her lip kits, promising her followers that they could replicate her famous pout. Now, she sells eyeshadows and eyeliners, and is broadening her range later this year.The star also makes what is rumoured to be tens of thousands of pounds through Instagram influencing, being paid by companies to endorse their products.