How does "because I refuse to let the fear of criminals dictate where I go and what I do" work as an answer?
Why does anyone carry anywhere? To be prepared. Are large gatherings of people the types of places the dangerously insane target? I think the events of the last few years make it obvious that they are.
What is the alternative? Cower in fear behind closed doors? Avoid public places with large numbers of people for fear of the whack-jobs and nut cases?
Doesn't sound like much of a way to live to me. I don't go to movie theaters, mainly because the tickets are ridiculously priced. But if I do decide to go to one I'll be carrying. Just like I carry pretty much everywhere else I go that it isn't prohibited.