For me, the biggest is definitely Modern Baseball.

To set the scene, it's 2016, I was in high school, and a girl I was friends with told me about this band Modern Baseball. I liked them a lot, but I wasn't quite at my peak emo phase (that would come about a year later during my freshman year in college lol), so I didn't get super into them or anything. Anyways, a few months after that, MoBo came through our city on tour and that girl and one of our other friends literally offered to pay for my ticket to the concert if I DDed for them... and I said no.

Fast forward like 7 months and Modern Baseball goes on hiatus in early 2017, a hiatus that continues to this day, though they played a few one-off shows throughout 2017. Anyways, fall 2017 comes around and I listened to Modern Baseball more and realized I really liked them... but they're on hiatus and I missed my chance to see them!

Anyways, I mostly made this thread because the fact that I turned down going to that concert is something I still think about from time-to-time and I wish I went, but I'd love to hear if anyone else has similar stories or just stories of bands you wish you could have seen.

The full podcast episode is worth watching, but I was absolutely blown away by all the tracks they played together and so wanted to share them here for any other QotSA or Norah Jones fans:
Make It Wit Chu @2:51
This Lullaby @15:13
Kalopsia @27:21
Somethin' Stupid (Frank & Nancy Sinatra cover) @51:16