Mental illness victim blaming goes something like this:
"This child was affliction-free until, at the age of 17, they smoked marijuana. As a result, they now have Down's Syndrome"
I'm using Down's Syndrome as a visual because everyone is familiar with it. This is strictly to illustrate a point.
The point is that people will magically forget a person's genetics, family health history, childhood symptoms of a given disorder and life events. They will also magically lose all sense of time and own hypocrisy.
This had happened to me. I had childhood symptoms of autism including key behavioral traits, ADD and a larger than average cranium. I've witnessed a traumatic event as a child and very possibly developed PTSD as a result (not yet diagnosed). I've been rumored to be on drugs while going through hell working at Walmart on third shift and being bullied, but nearly every employee I've known does more than just the big three (nicotine, alcohol and weed) while I only do the big three. Pill poppers were abound (and I'm religiously against taking other people's prescriptions, especially for recreation). I had vaccinations, and as soon as my mother knew, everything else she had clearly known about my autism from before the vaccinations magically became irrelevant to her. To her, the vaccines caused my autism after I showed the clear signs of autism she recalled for getting my diagnosis. WHAT?!!
When someone with a mental illness does marijuana, instantly, INSTANTLY people blame the condition(s) on the victim. It's extremely insulting and utterly moronic.
And no, it would not surprise me if this had happened to someone who has schizophrenia, PTSD, Down's Syndrome, progeria, fragile X or AIDS. It's that real and it's that bad. I'd have to write one to two pages more if someone needed me to clarify the above any further.
TL;DR: People only look at the first thing they would look down upon, such as smoking marijuana, think correlation implies causation and shut down all brain cells but what is needed for them to fallaciously blame the victim.
This is how prohibitionists think and its all too similar to the worst of antivaxxers, the ones who should clearly know that both biology and the laws of physics don't agree with them but then suddenly forgot, because drug use is easy to blame by the greatest of simpletons. It's a culture. It's a religion.