Actually, they arent as far away as you think - supernovas happens in our galaxy too. We are just lucky that our planet isnt located in one of spiral arms, where they happen more often. If it was, human kind and our civilization most probably wouldnt have time to develolop. But even with that, its almost certain that some of mass extinctions in history of our planet were caused by supernovas, they just werent close enough to wipe out life completely.
Considering that how large the universe is, and how old it is there must have been some civilizations that were wiped out by novas, or some other catastrophes like collision with meteorite. Things like this just happens spontaneously.