I had tickets for the Cramps- but got knocked off my bike and ended up in hospital
I had tickets for Dio and was so excited and spent weeks singing Holy Diver but he cancelled and subsequently died. We had tickets for Slayer once and they cancelled and rescheduled but the rescheduled date was when we were on holiday. I did see them but not on that tour.
Muse in teignmouth - I'd just started a new job, had no money, didn't want to risk being less than 100% the next day. Pretty much the entire department went.
And Reel Big Fish played when I was 39wks pg. I nearly emailed the venue and asked for a special seat! But realised it was pointless when I needed to nap 5-8pm and then go to bed at 9pm.
Way back in 2002 (or something), Incubus played Reading. I worked in a pub in a nearby town. Cue EVERYONE I knew coming in on their way home telling me how amazing it was. I almost cried behind the bar.