How can you quantify that statement? It's impossible without some kind of evidence [which will be subjective anyway]. It's an extremely damaging thing to say. There are people who are reading this, who will take that in and think, "oh, so I am not on the end of toxic behaviour, maybe it's my fault?" and will begin questioning themselves. That's an awful train of thought to have to deal with.
"Some of", fine, OK, understandable. But 90%? I would urge you to reconsider that figure. I have been on the receiving end of toxic behaviour, and one of the worst things you can do is start believing [as these people make you do] that it's actually your problem.
I am sorry, I am going slightly off topic, but I couldn't let that comment go. I think it's a very irresponsible thing to write on a public forum and it's important that it's addressed.