Here's what I will say. I smoke every day. It's legal, cheap, and readily available in my home state. I think that comparatively, it's less harmful than other narcotic substances like nicotine and alcohol. HOWEVER, it is addictive and not without downsides. It increases tiredness and apathy, and can make you more prone to procrastinating. It is also painful to be without it, if you smoke every day, as you will experience withdrawal. And once you have easy access to it, it's very likely that you will become addicted. I'm not sure that it's generally good for society on the whole, but I can't be sure one way or the other- I am more skeptical of it than I once was, though.