[anigbrowl]

I wouldn't be. That's the basic rationale of terrorists (both the foreign and domestic varieties). I don't think the Boston bombers were motivated by a specific hatred of athletics fans, or other demographic characteristics of their victims; they just knew it was a big static crowd with lots of media and weak security. The primary product of a terroristic enterprise is 'a scene of carnage' intended to communicate an experience of trauma to as wide an audience as possible.