Just try it. At least once. Don't like the smoke? Have a cookie. Within 15-20 minutes, you'll be wondering why you can't get marijuana from a liquor store, taxed and regulated in a similar manner to the rest of the products they sell there (which happen to be far more harmful to you and society anyway).

Side effects from over-doing it are basically mental slowness and a lack of motivation (even this will go away if you just stop for a while). If you start sucking at your job, your suckiness should show up on your performance review and HR should handle you accordingly. Maybe you get fired. This is how an alcoholic would be handled, anyway.

There is way too much fear and over-analysis surrounding this topic. The tools to manage it are already here. Marijuana is already here, and will continue on just fine regardless of whether it is legal or not. Overachievers like Michael Phelps and Barack Obama will smoke marijuana and go on to do great things, just as they always have.

Just legalize it already so we can finally benefit from California's number one cash crop, out in the open, rather than letting the majority of the profits go into the pockets of people who very often do pose a credible threat to society and require insane amounts of tax dollars to manage.