How do Kylie Jenner and the 4 other youngest US billionaires spend their time and money?

Who are Evan Spiegel, Bobby Murphy, Lukas Walton and Julio Mario Santo Domingo, and how did they make the list?
The five youngest billionaires in America have a combined net worth of US$28.5 billion.
Kylie Jenner, the youngest billionaire in the world, spends much of her fortune on new homes, customising luxury cars and holidays with her baby daughter, Stormi Webster. Jenner is known for flaunting her wealth on social media, as she did after chartering a US$200 million superyacht for her 22nd birthday celebrations.
After Jenner, there is Snapchat co-founder Evan Spiegel, who, at 29, is also one of the world’s youngest billionaires. Spiegel takes a more low-key approach to how he spends his time and money, especially since marrying model Miranda Kerr in 2017.
Spiegel and Kerr reportedly live together in a US$12.5 million home in Brentwood, California, and also have an oceanfront Malibu cottage worth nearly US$2 million.
Here’s how Jenner, Spiegel, and America’s other youngest billionaires spend their time and money.
1. Kylie Jenner, the world’s youngest billionaire at 22, has a net worth of US$1 billion
She spends much of her fortune on luxury cars, holidays with her daughter, Stormi Webster, and accessories like handbags.
Her car collection alone is reportedly worth millions.
According to E! News, the 22-year-old at one time owned four homes, including three in Hidden Hills, California.
According to the charter listing, Tranquility costs over US$1.2 million a week to rent.