Which is now available due to the ubiquity of usage, and which only came to be known in the last half of the twentieth century. It took hundreds of years for people to realize the death and destruction caused by tobacco usage.
This is what I mean when I say that people starting out on drugs simply do not know what they are getting in to. They are starting out blind and with a presumption of harmlessness, and the reality of the addictive effect of drugs doesn't manifest until it has already grabbed them. And then it is too late.
The harms of marijuana are likewise now well known - and if that knowledge is less widespread than for tobacco, IMO that has less to do with the dwindling frequency of 'it's harmless' claims than with the hysterical nonsense spewed by anti-marijuana zealots, which feeds the notion that all negative statements about marijuana are nonsense.