Drugs I agree...to a point, but I don't count weed in that group. It's impossible to OD on, and is great for cancer patients, arthritis, and anyone with suppressed appetites. That said anything you smoke is bad for your lungs. Ciggs, weed, camp fires whatever. Smoke is always bad for you. As for long term well, here's the catch. Weed does rewire the brain. Think of focusing to the point of tunnel vision on one subject. That's the reason when people are high every idea they have seems like it's earth shattering. At that moment their brain is in a closed loop. Firing the same string of brain cells over and over. Now for someone who has trouble focusing this is good. It allows them to hold a train of thought. We're talking long term use here since the effect of closed loop when high partially sticks with you after. After years of heavy use how ever you then rewire the brain to that of the stereotype stoner. So all things in moderation.