Most people don't believe a bomb will actually blow up or something on campus. I think what freaks people out is notion that the person(s) making the bomb threats are trying to observe the patterns and behaviors of how people react during an evacuation.

Pitt has the tallest educational building in the US (Cathedral of Learning - which has had 14 bomb threats), plus many other buildings on campus are rather tall too. I cannot begin to imagine how exhausting these bomb threats have been to the police. Many people don't want to evacuate the buildings either. But what if some lunatic takes advantage of how desensitized and relax people are becoming to go a shooting spree... that is the more scary thought.