Looking at the con horror stories everyone else has, mine isn't quite so bad.
The third convention I went to, I was completely alone. My friends had to drop out at the last second, leaving me to room with a pack of strangers. I sort of knew one of them, but the rest were complete unknowns. I almost had a breakdown Friday night after walking the con alone for hours (on top of being sick), but I ended up taking a shower and going to bed after the masquerade. I fell asleep on the chair. Good times.
The next day I didn't care quite so much about being alone and really enjoyed being able to go to whatever I wanted without a friend attached to me every moment. In retrospect, 16-year-old me probably shouldn't have been wandering around alone, but if it's any use, I was wearing a terrible Tsukasa (.hack) cosplay and nobody bothered with me.
I have so many more good con experiences than bad ones, and for that I count myself lucky.