Smoking marijuana is NOT bad for you?

I'm so tired of all the propaganda the government is throwing at us, IT HAS BEEN PROVEN IT DOES NOT KILL BRAIN CELLS, there have been no cases of any kind of lung cancer, and in 10,000 years of use 0 Deaths. If there had been a death or a case of cancer, don't you think the government would be throwing it all over the media? The only reason it is not legal is because the pharmaceutical company's wouldn't be able to sell it, because it is simply a plant. All you need is dirt and water to grow mass amounts by yourself.