very simply---(*spoiler*) if they properly holed up with the gun, they would have scared off the strangers...
But nevertheless, the idea/event of home invading is on the rise, it's only so undisclosed because rich people don't like reporting that they were home invaded...(to further protect their neighborhood)
I had nightmares after this movie, and I dreamed a friend was stabbed to death (oh dear), a friend I haven't seen in about a year, but nonetheless I had to go on thefacebook to see if he was still alive (yup, and in good health).