There are none so blind as those who will not see. Multiple people have told you they know people whose lives were ruined by it but you don't care do you? May I point out that denial like that is considered a symptom of drug use and addiction.
Thank you for proving that relaxed laws do increase use.
The number of people self admitting for rehabilitation of marijuana use has doubled in the last few years. I gave a link to a forum for families who are dealing with relatives who are users in order to receive support from others in the same position. The first post I ran across was a mother at her wits end. Now tell me that there has been no effect and back it up with actual facts.