I don't know where you found your information, but marijuana has its side effects. Especially when smoked. When smoked, there is a significant intake of carbon monoxide and tar, even more than smoking tobacco. This is information backed by the New England Journal of Medicine. The average marijuana user uses on average about 2-3 times a month. With just this kind of intake the effects can be negligible at first but can develop to lung inflammation and regular coughing later in life. Prolonged lung inflammation could devolve into much worse problems including but not limited to heart failure. All this is just for the average user. If used on a more frequent basis, smoking marijuana can have the same, if not worse, effects on you. All that talk about marijuana lowering the chances of cancer are untrue. You still inhale carbon monoxide and you still destroy your lungs opening you up to lung cancer. You may be wondering that all this is about smoking it, but what if you don't plan on smoking it? What if you just want to eat it? Well it's got it's fair share of side effects that way as well. Cannabis can cause hallucinations, changes in mood, amnesia, depersonalisation, paranoia, delusion, disorientation, difficulty to focus, insomnia, sometimes even depression. You may also feel unnecessarily hungry which can sometimes cause an increase in body mass. All in all if you were thinking about it don't do it. The effects of weed aren't as light as you make it sound. It maybe legal in some places, but so are cigarettes and vodka which could literally put you in the ER if you manage to down a whole bottle quick enoug which is actually possible. This is all scientifically backed and it's always better to listen to science than people's experiences.