Case in point:

News story some years back: In a community north of Seattle, a man living in a small house got up from his easy chair to change channels on his TV set (before the widespread use of remotes) and just then he heard a loud "bang" above and behind him.

A bullet had come through the ceiling of his house and buried itself in the seat of his chair. If he hadn't gotten up just that at moment, the bullet would have gone through him nearly vertically.   

New Year's Eve and on the Fourth of July, things can get a bit dangerous because of the habit of some numbskulls who step out one the front porch at, say, midnight on New Year's Eve and fire a couple of celebratory rounds in the air.

Things that go up do tend to come down. Rare is the firearm that propels a bullet fast enough to achieve escape velocity. And in a populous area, such as a city....

Including shotgun pellets raining down at terminal velocity....

Not good!

Don Firth