I don't know if hash robs you of your ambition, but it's certainly possible it may makes you feel that everything is already irie so why bother challenging yourself.
We all lie to ourselves about how successful we are and how close we are to realising our dreams, this is a healthy delusion though, if you didn't wake up thinking that everything is possible and that things are more likely to go better than worse you are adding yourself to the list of things that need to be overcome. I think it's possible for your sense of deferred gratification to get muddled with hash, and you absolutely need it to succeed in anything.
I guess I'm like most of the smokers I know, I indulged rather heavily in my 20s and slowed down to a couple of times a month. Doesn't hold the appeal it used to, but I can still get into it once in a while.