If you are completely fine with alcohol and cigarettes, then there shouldn't be a reason you aren't accepting of marijuana as well. A 2010 study published in the Lancet and reported on by The Economist, a team of drug experts in the U.K. assessed the combined harms to others and to the user of marijuana as less than the harms posed by alcohol or tobacco use. The negative stigma of pot use has certainly made it seem like it's worse, and since using the drug is still illegal, the fact that only people who are willing to break the law will smoke has inevitably made it associated with a pothead culture.
