Because that doesn't seem to be factoring into your analysis of the source of the impairment.
If I told a story about a kid who showed back up at band camp and had become 50 pounds heavier and hadn't progressed as a drummer, then went on to become a heroin addict etc. you wouldn't be blaming cookies. You'd stop and wonder what the hell was going on in his life.
I wasn't aware that cookies cause paranoid delusions.
Marijuana on the other hand…[0]
As I mentioned, I grew up with several kids like this. Most didn't attempt suicide (as far as I'm aware, anyway), but the possibility of confirmation bias aside, I certainly feel as though I recognised a pattern of paranoid delusion among young stoners that I knew.
I grew up in a super poor neighborhood, and I knew maybe 10-15 kids who started smoking MJ before age 16. The only ones who had any kind of extreme cognitive fallout were the ones that dabbled in more extreme stuff (like PCP). Even in those cases though, it's hard to point at the drug as opposed to the reason they were using. (In the PCP case it was three brother with a mentally ill single mother)
I'm not discounting the possibility that MJ can cause such things, but even the studies put the risk fairly low, and it's hard to separate environmental and genetic risks in the population they have available to study.
If I told a story about a kid who showed back up at band camp and had become 50 pounds heavier and hadn't progressed as a drummer, then went on to become a heroin addict etc. you wouldn't be blaming cookies. You'd stop and wonder what the hell was going on in his life.