Since ppl obviously disagree with your view - here is some anectodal counter evidence:

When i was younger and went out often, I had a close friend group of like-minded ppl. In that group we experimented with different drugs. The most common one was probably MDMA in pill form, but we had things that where in powder, liquid, crystal and organic form. For new drugs we read up and usually had a trip sitter, all our stuff went through the lab - so we knew what actually was in there. In our high time, we had a trip every weekend and a comming down with some weed. I know for a fact that we did not harm anyone else. Did we harm our bodies? Possibly, but for sure less than smoking tobacco for the same period and frequency would have. Did we develop an addiction? I can't speak for the others, but i know i did not. And those i am still in contact with have a clean and organized life now.

It will be extremely easy for you, to simply say 'denial' and not take in what i wrote. But trust me when i say i know what an addiction is. During my time in the military i developed an addiction to alcohol. I am fine now, but i know how it is to be dependent on a substance and i know how it is to look back at it.