Why did Kazuki Takahashi stop creating manga after Yu-Gi-Oh? Being a long time fan of Kazuki Takahashi's Yu-Gi-Oh! series, I tried to look into any manga that he may have produced after the completion of Yu-Gi-Oh!: Millennium World, but it seems like he just stopped writing manga after that.

Is there a reason why he stopped?
Mangaka tend to be somewhat reserved about their personal life. Takahashi has said of himself that he is great at postponing, leaving work until the last moment.

As already mentioned, he created a one-shot called Drump in 2013. He continues to oversee the development of the sequels of Yu-Gi-Oh! since he finished the original series in 2004. He has also actively participated in the development of the card game. To date, derivative manga and the card game are still being published, so he must consume part of his time in that.

In February 2015, a new adaptation of Yu-Gi-Oh! was run in Japan. This was due to the production of Yu-Gi-Oh!: The Dark Side of Dimensions, the most recent film of the franchise that celebrates the twentieth anniversary of the brand, and of which Takahashi is the author.

In short, I have no information for sure, but it seems that he is quite busy with his other activities to create something else.