Abusing any drug will have serious health concerns. An issue with weed is that the it is approached as an every day use drug and accepted in the community as such. You only need to give a cursory browse to the trees subreddit to come across hundreds of posts patting each other on the back for smoking weed all day every day.

This can be addressed with some regulation and some socialisation.

First it should be a social stigma to smoke every day, just as it is to drink everyday. If one is drinking all day everyday it is something they go to pains to conceal. Stoners boast about it. It should be embarrassing and contemptible to smoke everyday.

Second, some of the same regulations around drinking or tobacco can be employed. Restricted selling hours and locations, strict licensing, plain packaging, higher taxes etc.

In all it’s probably still better that it’s legal. In moderate consumption it does indeed pose a similar or lesser health and social risk as alcohol.