My parents sort of made me go to my equivalent (in my part of Canada, we don't have "proms," but the senior year gets "grad," which is a speeches-type dinner and dance in fancy dress for graduating, which you technically don't do until after the event) because they wanted me to go. My mother made my dress, so we didn't spend anything (practically nothing even on the material, which she bought for pennies from a street vendor in Mexico). I sat with my equally odd friends (not AS, but OCD, social anxiety, that sort of thing) and we spent dinner talking about video games, didn't dance afterward, and took off as soon as we could to spend the night in my friend's basement playing Risk 2210. That was the only good part, to be honest.
(The other kids - and bear in mind, this is a highly-academic school that only accepts the top 100 students in the region, not a general high school - all went to "after-grad," got mind-blowingly drunk and did things too embarrassing even to type. Thank GOD I didn't have to go to that.)
If I'd missed the entire thing (better yet, if instead of going we'd just started playing Risk a few hours earlier), I wouldn't have missed a single thing I'd regret having missed.