He is a well known figure in chess. More people recognize his name in connection to chess than Magnus Carlsen and Fabiano Caruana combined! Of course he writes about chess - when he does people listen and assume he has something insightful to say (weather or not he does), thus when he wants money he needs to talk about chess. He can be (and reportedly is) a great inspirational speaker, but he is expected to talk about chess at some time in each speech.

He's "retired". It was just last month he was competing in a Fischer Random event with many of the top players today. [1] And he still regularly provides commentary, above and beyond that of an informal observer, on various games and events.

[1] - https://www.uschesschamps.com/tags/2018-champions-showdown

> he has no reason to keep writing about chess

What does that mean?

edit: I mis-read the tone of your message, ignore.