Can you give me a for instance, one that does not include the crowded spaceways of sci-fi?

Sol is a small, main sequence. A nondescript little star in a pod of main sequence stars that trail through the habitable zone of the Milky Way galaxy. There are literally trillions of them, with incredibly few passing within 10 - 50 trillion miles of each other.

It is not a close-knit community, and there are no ETs out there with designs on an already-populated system.

The danger is a real no-brainer, because our main threat is without intelligence. Our own system of planets, asteroids and comets -- along with whatever other little bits of flotsam is drifting around out there. Coupled with the enormous gravity-well of Sol -- which enjoys pulling whatever garbage it can toward it -- the system becomes a virtual shooting gallery, and lil' ol' Earth just happens to be dancing close around the bull's eye.

Dan