Nonsense; use is easy to hide, and abuse hard to hide, regardless of legality.
As for heroin, it's simply HIGHLY addictive.
And marijuana is less addictive than alcohol.
Ask most uses. Then ask them if they were introduced to psychotropic/narcotic drugs by using marijuana.
No, most of them were probably introduced by beer.
Slow work day? Still trying to say that alcohol and tobacco are the only dangerous drugs? You only lie to yourself.