you're right. however, pot is less terrible than alcohol in basically every way.
except that alcohol currently and historically has generated huge tax revenue. if i were the alcohol lobby, i would make damn sure than no other drugs become legal and taxed.
That's always a question of proportion. It's all in the mix. It's sure carcinogenic and surely beats the lung up in a lot of ways. It also does statistically, by my own observation, lead to a significant lack of all kinds of activities.
For example, it frequently leads to a lack of believe in - or even just consideration for - how terrible substance consumption is, over all if not for the sake of nutrition.
Also if you are prone to developing a psychotic disorder (prevalence of psychotic disorders is ~3%), pot consumption before the age of 20 increases the chances of it happening.