I think the worst thing is it makes you demotivated after a while. At first you feel like it's helping you with your creativity but eventually it becomes a crutch and you end up getting nothing done. I also have a friend with PTSD that smokes and I swear it's making him so much worse, but he won't take the time to get past the 1 to 3 month withdrawal phase to be able to see how much less stressed he is without it. At this point he's so deep into it that he's like a different person, constantly on edge and high strung. And it's not the PTSD either because when he first got out of the military he was vastly less bad off than now.