daily marijuana use has its benefits. but like any other substance it has negative effects when it is bein abused on a daily scale. like for instance lets say a gram a day is healthy, if you use that then you are following it as it is to be used. now lets say you know that a gram a day is recommended but you want to use 7 grams a day thats when you get into the more negative effects of use. the more you use the more bad it is for you.
Technically, it isn't directly bad for your health, studies show that most negative effects can be negated by not smoking it anymore. There really is no short answer other than it doesn't, but that isn't entirely true, if you're truly interested in the topic, you should research the topic a bit, but there is a lot of conflicting information so be careful who you listen to.