As I said, the use of alcohol is not even comparable. It takes years of heavy drinking (exceeding the BAC considered to be impaired several times a week) to begin to cause equivalent damage to what even casual use of marijuana or other schedule one drugs causes. Marijuana causes physical damage and alters the function of the brain. Furthermore, our bodies have a dedicated metabolic pathway that exists only to destroy alcohol. We have no equivalent for any schedule I drug, so they stay in the body longer, exacerbating the ill effects of the drugs.
I can tell stories of addiction, too. The addicts Ive known used a variety of substances. The addiction is the issue, not the specific drug used.