This "terroism becoming normal way of life," is probably too unnerving for many; they want to keep their heads in the sand, disbelieving what their common sense or gut instinct tells them.
For others, to some extent, their refusal to believe that the sniper is a terrorist is valid, in that we have had snipers, serial killers, copy cat sickos living amongst us in the past. We "breed" them and always will, just like every other country will have the same evil/sick people, unfortunately. And I think our liberal laws allow them to flourish more greatly in our country; they will be protected and know this; they scoff at us (I think of Manson) once they are arrested, if they aren't killed first.
Denial and doubt are useful tools for our enemies.