I know this was a sarcastic comment, but I do think the sentiment isn't too far off. You're talking about leaving a $1100+ device out in an uncontrolled and unguarded environment where you don't know and trust most of the people there. From both a personal information, and a personal property standpoint this is just highly irresponsible. You should seriously reconsider whether you should be bringing your laptop with you into this setting in the future. At the very least you need to lock your screen and use a Kensington lock. Either that or always be prepared to close your screen and go at a moment's notice.