Your conviction that marijuana is a benign weed needs re-examining.
That the wish can be the mother of the thought is well-demonstrated around here. I'm sure the nature of marijuana is perceived by you to be benign and has been benign in your reality.
The heaviest users, the most addicted, also say it's benign. And meaning it, they would pass lie detector tests at the time. It's the nature of the drug, sort of like mosquito or leech bites, to anesthesize the areas it's taking out.
Marijuana is benign for most people, as are alcohol, cocaine, methamphetamine and heroin. I would modify your statement to say that marijuana is a toxic weed which can be used in a benign manner by many people. That would seem to cover everyone's experience with it.
Arf