Just so cynical. TSwift is huge everywhere. And tickers are nowhere near expensive enough to be limited to trust fund kids. A majority of that audience is middle class and the tickets will be varying levels of affordability. For a small portion of that audience the show will be a multi year saving situation and will be the highlight of some childhood dream.
Unless you have some kind of medical issue, you could just go to the toilet before and after and drink very little during the show. If you're there for the music and not just to get drunk, that is.