Let me assure you that all the people that I know that still use marijuana and use it on a regular basis have been in jail at least once, divorced, paying child support, unemployed, and involved in many domestic disputes.
Which is the cause and which is the effect? Hard to know, isn't it.
Is marijuana bad for you? Probably. How many people do you know who have serious drinking problems who have also been divorced, unemployed, serious health issues, etc?
I've met more than few people that got liquored up and then got stupid and aggressive. In contrast, people who smoked dope generally just chilled and dozed off.