Doubletap, it could be that the fellow smokes dope because he's a slacker, instead of him being a slacker because he smokes dope...
I'm not so sure about that. I know one gentleman whose life was essentially ruined by a lifetime of smoking grass. He was my best friend since age 8, and was an energetic, enthusiastic fellow in everything he did, and was one of the best artists I've ever seen.
In 1969, we both joined the service, and he started smoking dope. Since then it's become an obsession with him, and that's all his life centers around any more. He no longer has any ambitions, energy, or, it seems, any hope
. His artistic talents no longer exist. Where he used to be meticulous about his appearance and belongings, he's now a slob and his home is always in disarray.
I knew this fellow well both before and after, and while my observations might not be scientific cause and effect, I think it's a pretty solid bet that it's the primary factor in ruining a good man.