Glastonbury used to be one of those places that you felt 'safe' - where people automatically looked out for each other...it might be different now, but then again, in those days we only paid £21 for a weekend ticket...lol
Great story about the Hell's Angels. That is Glastonbury at its best.
I found it got to feeling a bit unsafe in the late 90s, when lots of people were jumping the fence intending to kit themselves out for the weekend by robbing tents. I remember overhearing more than one conversation passing by when it was clear that this was what happening. I started knowing far too many people who'd come back to find their tents had entirely disappeared.
For me the nadir was '97 (a
very wet year) when I had someone sneak into my tent and steal my wallet from beside my head while I was sleeping. I woke up just in time to see a backside disappearing out into the 6" sea of mud outside, with me dressed in little more than boxers and a t-shirt. I was still enjoying the after-effects of some extremely good Welsh grass that had accompanied watching The Prodigy, mind you.
Amazingly, Somerset Police did return my wallet a few weeks later after it had been found in a ditch, sans cash.
The moral is to keep your valuables very close to you, preferably strapped to you.

The bottom of your sleeping bag at your feet is not a safe place as I've heard stories of people slitting them open with a knife.
Things did seem to improve in the early noughties, to be fair. I've not been since 2005 due to the apparent impossibility of getting a ticket and then the arrival of a baby.