Well one major change to his politics was his view on climate change. He also supported Obama in both elections, and had the self-control to keep pretty quiet about issues unrelated to his business.

I found the article I was talking about: https://alisoncrosthwait.substack.com/p/a-ketamine-addicts-p...

It says it's quite easy for ketamine use to get out of control without the users noticing, that they're are able to work effectively despite that, and that they tend to develop radically different and delusional beliefs. Given that Elon has admitted to self-administering ketamine, I don't think the idea should be dismissed.