I'm not making light of your outrage. I consider the crowd's reaction to be a good sign of the mood of American consumers toward performers. Unfortunately, the tickets had already been bought and paid for, or there wouldn't have been thousands of people to begin with...but how many tickets will she sell now?
Without that kind of activism, without people seeing other people outraged, some might accept it as the prevailing opinion and then as their own.
People have a herd mentality. When not sure about their own views, they skeddadle to the relative safety of majority opinion. Sometimes they never figure it out for themselves. The left for decades has been using peer pressure as a technique to not only keep their own troops on the straight and narrow, but also to manipulate mass opinion.