For every story like this, there are way more stories of senseless violence and accidental deaths.
If a household has a swimming pool and a firearm, the probability of a child dying in the pool is over a hundred times more likely than dying by the firearm.
If somebody breaks into your house, they're not dropping in to have a cup of tea. Furthermore, the cops cannot be everywhere at all times. These are sad realities, but they are reality. People should be free to choose whether or not to protect themselves in their household.