Tell me how exactly you safely consume marijuana? Please don't spread disinformation like that. I am not the one to judge you, but if you through all means try to good-talk your faulty behavior, this is a sign of addiction.
I encourage you to read the following page and seek help before it drags you down to a place you cannot recover from. It's not too late.
http://www.helpguide.org/mental/drug_substance_abuse_addicti...
For some however, it is a very real solution to problems like anxiety, insomnia, depression, low appetite, etc. Marijuana often has fewer side-effects than medications prescribed for those same ailments, making it a better option for many. That is how some people justify consuming the drug, and I think it's pretty narrow-minded to assume anyone who makes such a justification is an addict.
Because someone doesn't adhere to your standards, they are weak? That's a pretty poor outlook. Besides, there are perfectly safe ways to consume marijuana that aren't destructive, as with just about any other substance.