My reasons- You're smoking it. It involves fire, and paper, and weed, so carbon dioxide and monoxide poisoning. People decide to smoke it then go outside. It makes a place look horrible but also, when you're not quite there and decide to drive a car or motorbike and hit someone because you're not thinking, you've probably killed that peeps on. It's illegal (unless you're in Paraguay, North Korea, Luxembourg or one of the four states in the US who have legalised it). Just accept it rather than getting into all the court trouble and paperwork. Gateway drug. It might not kill you but what it leads to will.