Here's one of those fact checking articles that attempts to refute the whole notion of mass formation psychosis.

It's main argument is that this is not a term that is found, well, it doesn't exist, and their proof is that experts say so, so there. Here are some excerpts:

Psychology experts say there is no support for the “psychosis” theory described by Malone.

No support? If I support it, does that not count? No, it doesn't.

“To my knowledge, there’s no evidence whatsoever for this concept,” said Jay Van Bavel, an assistant professor of psychology and neural science at New York University who recently co-authored a book on group identities. Van Bavel said he had never encountered the phrase “mass formation psychosis” in his years of research, nor could he find it in any peer-reviewed literature.

Well, there you go! So, now we know that group identities exist, but mass psychosis doesn't! When, exactly, does a group go from just a group to a mass? That's my first question.

The term also does not appear in the American Psychological Association’s Dictionary of Psychology.

Clearly the gold standard of credibility.

Richard McNally, a professor of clinical psychology at Harvard University, wrote in an email that people who support COVID-19 vaccines and public health guidance are not delusional. Rather, they are “fully responsive to the arguments and evidence adduced by the relevant scientific experts.”

Well, I can tell you that this is 100% incorrect. I am fully vaccinated, so in that sense I support the vaccines and public health guidance, but I am certainly, positively not “fully responsive to the arguments and evidence adduced by the relevant scientific experts.” Therefore, Dick's entire premise is incorrect. He's making an all or nothing statement. Dick, you're wrong. I am proof.

And it goes on.

One thing that gets me is that nowhere in this detraction does anybody address one of Malone's claims -- that the group think (does that work for you, Jay?) is supporting government and corporate covid policies in an unquestioning, irrational manner similar to how the Germans supported the Nazis. What they aren't addressing is how did the Nazis get good Germans to support the extermination of the Jews? If that wasn't some sort of mass psychosis, what was it? What's the word for that? Because it is that type of irrational behaviour that is happening on a mass scale, whatever you choose to call it.