It's a waste of time arguing that many of those homeless on the streets are mentally ill due to their excessive drug use. It's widely accepted among the medical and scientific community.
Many of the homeless living on the streets are completely whacked out. It's directly due to their abuse of drugs. Meth, ketamine, fentanyl, and now xylazine. It's turning people into crazed zombies. People that have had normal lives for decades without any signs of mental illness that have become addicted to the nasty drugs on the street are now raving lunatics resembling people with schizophrenia and other mental disorders.
It's obvious that some don't see this crap day after day so I understand that they are clueless to what's actually going on in many cities. But to argue that it isn't a cause is ridiculous. I've seen normal people literally go crazy from some of the stuff people use to get high.
"Addictive drug use or prescribed medicine abuse can cause psychosis. Some representative symptoms frequently elicited by patients with psychosis are hallucination, anhedonia, and disrupted executive functions. These psychoses are categorized into three classifications of symptoms: positive, negative, and cognitive. The symptoms of DIP are not different from the symptoms of schizophrenia, and it is difficult to distinguish between them. Due to this ambiguity of distinction between the DIP and schizophrenia, the DIP animal model has been frequently used as the schizophrenia animal model. However, although the symptoms may be the same, its causes are clearly different in that DIP is acquired and schizophrenia is heritable. Therefore, in this review, we cover several DIP models such as of amphetamine, PCP/ketamine, scopolamine, and LSD, and then we also address three schizophrenia models through a genetic approach with a new perspective that distinguishes DIP from schizophrenia."