>but people have a visceral negative reaction to arbitrageurs since they didn't do anything to "earn" their profits

I don't think there's anything wrong with getting money that you didn't earn (so long as you're not exploiting people, as the bourgeoisie do); I do think there is something ethically questionable about forcing (I use the word 'forcing' to refer to the idea that within the confines of show-going, it is the only available choice) people to pay 3x more for something out of greed.