I'm no expert, but I think weed definitely promotes psychotic thoughts. More so, the stronger the THC content, and the longer and frequent the use of it. In very rare cases this can trigger Psychosis, but in most people it will not.

Rather what you tend see in daily smokers is a attitude of mild delusional distrust, often leaning towards conspiracy theories, anti-authoritarianism, etc. Since many are not aware of any unreasonable thought patterns, it may be seen as a mild form of psychosis. It goes away only 1-3 days after stopping consuming it though.

But I think it's worth keeping an eye on, in this day and age, we really don't need more people following misguided errands.