I had once stayed with freinds that did drugs to the point where they forced me to take them. 
My friend dave was one of my bestfriends that was a drugy that i convinced him that its not the right way to go, that there was another way to be a success in life. He replied back in a depressional voice " maybe.. but i dont think there is another choice." i told him in return " Soon your gonna realise what youve done and thats why I'm telling you now to not turn into a monster". Few days later i wasnt friends with those who did drugs because it was too much and they were forcing me to do things that i have felt very uncomfortable with doing like doing weed or smoking other stuff that i dont know what they have or having drinks that smell funny that make me feel light headed from just smelling it. Also on the same day my friend followed that same path as well and had seen what happens to yourself and how it makes you into something else than what makes you you.
So now Dave and I are now living as drug free people and we may have one or 2 that do drugs but never encounter them ever again as we seen what they can do to ours and your life.