I find it difficult to believe that it's a foregone conclusion that more than 2/3 of adults in the United States of America, my home, have involved themselves with an illegal drug.
I'm not doubting the study, I can't grasp the outcome.
Cannabis is not some terrible thing that turns people into thieves and low-lives. Plenty of the people you interact with every day (and likely have pleasant interactions with) use these substances. Perhaps some of this is location based, as I know on the west coast the general consensus is that people don't give a damn. Every single person I know has a friend or family member that smokes, often times successful and happy people, and it's not a big deal if they do or they don't. Public sentiment is changing every day and I truly believe that in the next 20-40 years cannabis prohibition will be a thing of the past just like alcohol prohibition.
One question for you - which do you think causes more health and addiction problems for people in the US ? Cannabis ? Or alcohol and prescription medications ?
People also download music, drive over the speed limit, and call in sick to work when they're perfectly healthy. The past three presidents have all admitted to trying illegal drugs. What's so surprising?
Your last line seems to imply that you doubt the results of the study, but that's a bit ridiculous to do based on personal anecdote.