Rachel, you are SO wrong. Since 1950, EVERY mass shooting except 1 (Gabby Giffords) took place in a "gun-free zone". Sane or not, the bad guys choose where to commit mayhem. The Batman shooter drove past several theaters which allowed concealed carry, choosing a theater in which the law-abiding were unarmed.
In Britain, 1/3 of burglaries are "hot": they occur when the homeowner is home. This is an extremely dangerous situation! In the US, "hot" burglaries are rare because the burglars avoid occupied homes, saving lives.