You won't find this person in Forbes, although they should be. They literally have at least a billion dollars and have taken advantage of their position in the entertainment industry to make all that money. Oh, they don't have a makeup or clothing line. They have never licensed any bottles of perfume. They have never sold overpriced sneakers and prison clothing and called themselves a designer. This person is a writer/singer with the emphasis more on writing. About a decade ago, they were just starting out and someone needed some rent money, and this writer/singer helped the person out. They got paid the next week and the person who paid them back added 10% to the amount loaned.
Our singer thought nothing of it until a few months later, the singer realized they were fronting a dozen rent payments a month and getting 10% on the loans. Nothing was ever formalized, it was unwritten. Within a year, it wasn't just apartment rents, it was mortgages, and car lease payments and so much more. The singer was making far more money loaning money than singing or writing, but the loans led to more singing and writing jobs because the singer/writer suddenly knew everyone. The singer/writer never traded jobs for payment on loans, but did accept transfer of copyrights in lieu of payments on loans. Many times the copyrights being transferred were not worth all that much, but samples could be used royalty free now and that was helpful. Also, there were some very big copyrights that were transferred. Our singer/writer has saved lots of homes from foreclosure and also bought homes and then leases them to the previous owners when they couldn't catch up on payments. Just in real estate this singer/writer probably has $400M in properties scattered across the country. They own stakes in probably 500 franchises that each make money. They own copyrights that generate tens of millions of dollars a year in revenue. They own catalogs of recordings and even the rights to a series of books that has sold millions of copies.
Meanwhile, they just keep writing and singing and keeping their head low while they work with A lister after A lister, many of whom are actually in debt to the singer/writer.