According to Celebrity Net Worth, Kazuki Takahashi was worth $20 million. CBR reports that the Yu-Gi-Oh! card game first came out in Japan in 1999 although it was released in North America in 2002. In 2021 alone, the game had not only sold 35 billion cards but grossed over $9.6 billion. Over the years, the game has also seen a number of updates and changes which can also encourage sales. But older formats are still popular and it all really depends on how individual players want to enjoy the experience.

Although Yu-Gi-Oh! Master Duel is free, it features in-game purchases, and the versions for iOS and Android contain ads, generating even more revenue for the franchise.

Yu-Gi-Oh! has more than just game cards. There are accessories people can use to play the games, like the Duel Disk that is featured in the anime, and other kinds of merchandise. At Hot Topic right now, for example, there are all kinds of things like skateboard decks, ramen bowls, figurines, wall art, and more. Now that Takahashi has passed, it's not clear who will get the money from Yu-Gi-Oh! related sales.