It’s bad because its illegal. Why is it illegal? Because it’s bad.
Anyway, part of the problem answering this in General Questions is that nobody in the US is allowed to do any medical studies on Marijuana.
Nope - there’s no LD (lethal dose) for cannabis. The argument that says Yes, marijuana killed someone because he was high on it when he drove off the cliff is not far from the story my old science teacher used to tell us: A guy he knew was killed eating marshmallows. Seems as if the guy ran out of marshmallows and went to the store to get some more, and while he was walking across the street, a car hit him. When someone says marijuana can’t kill you, they are saying that there’s no amount of the substance that will kill you, and that’s true.
There appears to be a LD50, e.g. 1.2g/kg in rats. In humans there are no clear estimates, but guidelines suggest as much as 1500 pounds consumed in a very short period of time. So knock yourself out, it’s completely unfeasible that it can directly kill you.
Similarly, while nicotine is pretty innocuous in humans (it’s not the bad part of cigarettes), you can kill someone if you concentrate it, way beyond anything that can fit in a cigarette.
Take that shit to the “New Zoo Review news”