Okay, sure, you judged them before you got in there, but there are two big reasons for you to not be disappointed with yourself.
1. You thought the situation would be bad, but you went anyway and showed your commitment to the cause of the day, your confidence in yourself, and your willingness to try something, even if there is a cost. "The worst that could happen is that I would get beat up" is a great philosophy, in my opinion. People seem to always run from imagined negatives, but taking them as part of life and seeing them in context is admirable.

2. You're willing to admit that you were wrong about your ideas, and you actually felt bad about expecting the worst. The ability to change your perspective is just... civilised. You could have easily come to the conclusion that you 'just got lucky this time', but you didn't.

Did you guys end up raising enoug money that night?