I've seen research that suggests Marijuana may be detrimental to mental health, particularly in young people. There is also evidence of IQ loss with habitual use. I presume it is not without cost.
Alcohol, of course, is one of our greatest killers, and there's plenty of evidence of harm to both physical and mental health, as well as collateral damage to family
Now, just because one thing is really bad, that doesn't mean we should do another less bad thing. But there might be an argument for substitution (like vaping nicotine for smoking cigarettes). And, of course, I believe people can make that choice for themselves.
As I get older, I find I get less and less pleasure from alcohol, other than wine accompanying a good meal. My microdose experiments with edibles and dry-vaping (~5mg THC) have been *very* noticeable and enjoyable listening sessions, and I've slept very well afterwards. The logical conclusion is I should quit alcohol and keep to occasional MJ microdosing. Will I do that? Probably not.