Did it occur to you that he was taking pictures of himself and his buddies for the sake of fond memories? That's what I do. I don't smoke weed even close to a regular basis, and I did a lot of research before I did. It was fun and and I have a lot of fond memories with me and my friends where we smoked a joint and just chilled. Good times.
Furthermore, weed has been proven by multiple studies to have medicinal properties, otherwise "medical" marijuana would've been a moot point and would've never been legalized. I also agree with you that smoking weed has it's health hazards. There's a shitload of tar and cancerogens you breathing in when you burn it. If that doesn't appeal to you, use a vaporizer.
It is however, without a doubt, far less harmful and beneficial than our friendly neighborhood legal drugs, like alcohol and the chemically doused tobacco in cigarettes. There is currently no recorded death or even case of cancer tied to marijuana use alone. It is impossible for you to OD on marijuana. You can certainly OD on alcohol, and alcohol can cause violent and destructive behavior. Also it causes liver damage, heart desease, dementia and depression, anemia, and cancer. I really don't think I need to school you on cigarettes. You're a grown boy who thinks he has everything figured out, you know the risks behind cigarette smoking. (i.e. multiple forms of cancer, stroke, impotency, emphysema, atherosclerosis, heart attack, etc.)
So no, based off marijuana use alone, you will not outlive me. Especially since I smoke periodically and not regularly.