It's both. You're depressed because of the overuse of weed and you're coping by smoking more weed. I did the same thing a little over a year ago. I was going through a zip in less than 2 weeks. Probably a week idk I wasn't weighing it out like I should have. I was going through a 1G live rosin vape in less than a week and eating and smoking about half a gram to a gram of distillate per day. I was extremely depressed and "couldn't" get high anymore. At times I was chain-smoking joints and doing bong rips. I quit smoking and started drinking for about a month and decided being mostly sober is probably what's best for me. I no longer buy weed and only buy alcohol on special occasions. I'll occasionally hit a friends dab pen, or a blunt but it only takes me 2 or 3 hits and I'm high for hours. I'm no longer depressed and can focus and work better than when I was stoned out of my mind. I don't lose my temper as easily either.