I heavily relate to your friend losing his mind and dying on an acid trip. I'll contribute my experience so maybe your friend might be able to snap out of it or others having the same experience can relate or find some comfort. My first time taking acid my concept of time completely flew out the window. Each moment felt like an eternity and my head started to fill with errant thoughts. It all started when I began to believe that anyone I had ever known was watching me. I FULLY believed that out the corner of my eye I thought I saw them, but when I turned to look, they would hide or something. I started to become afraid of being the center of this huge elaborate test or something that I had never caught onto my entire life. I started being afraid of turning around - scared of finding that my old friends, family, and random people had been watching me my entire life. This "realization" never really went away, I just ignored it and ACCEPTED that I couldn't handle the real truth. At this point I am huddled up in a corner COMPLETELY unresponsive according to my friends. The guys who dropped with me just left me there for a while, so that didn't help. Thoughts upon bad thoughts just piled up after that, as if my mental immune system had been disabled and my brain couldn't filter out any of the ridiculous things. It was absolute anguish the whole time. Eventually, I was pushed to the brink - I thought for sure this was how I was going to go insane and die when I absolutely couldn't take it anymore. Being now that I thought I was clashing with reality and that I could not accept it for what it was, I felt that I must be dying. I rationalized this was how people die. Wouldn't it make sense that people die when their world comes to an ultimate conflict with reality and they have to part from it, become unconscious or insane basically. I thought this was happening to me then. It makes a lot of sense to me, even now. At that moment I recall looking at my hands and at the spot where I had then died. I didn't feel any better but I did have some sort of closure from death, so I got up and started exploring what I thought was the afterlife. Nothing really made sense after that. I couldn't make sense of words, the TV, the people around me, what people were saying, or basically anything. My friends had already come down and thought that I had come down as well. I had many other thoughts and "revelations" during this but I can't remember them all. I did start to regain my senses quickly as the drug wore off, but I couldn't fully shake everything I had "learned". I felt depressed and dissociated for a week or more afterward. Luckily for me, I think what saved me was my critical and empirical mind set and I just couldn't cling to what is basically unsubstantiated and has no basis or effect in my everyday life. Basically I snapped out of it and realized it was my imagination was running rampant on my most subconscious and primal fears. I guess what I learned was that some thoughts just do not correlate to reality and should be absolutely let go for the better. Since then, I have tripped a few more times, had some nice trips, some more bad trips, but for the most part, they're a lot more anchored. I hope there's some basic truth in my experience that can help anyone that's had a similar bad experience. I'm starting to think it's N-bome and not LSD that's doing this, which really sucks.