I could be wrong, but I suspect that you're a few years younger than I am. When I was 19 I hadn't lost any friends yet. But there was a change coming over the Bay Area in the late 60s, and by the time that I was 22 calamity was everywhere. Schools began to have police on regular assignment, and some were even installing metal detectors in their entrances.
In some respects it was the good old days; I definitely had a lot of fun in the 60s but for some of my friends reality closed in and cancelled all the fun.
My guess is that I had a different childhood than you did and a wilder group of friends. I was always attracted to danger and unpredictable situations and that means that you associate with people that do things that get them killed.