It is the same benefit as carrying insurance (auto insurance, home insurance, medical insurance, etc). Most people pay into insurance and never use it, and you hope you never have to use it, so you might ask them why they need it and why they keep paying into it. The answer is that you have insurance because if you need it, and you don’t have it, it’s already too late to get it, and your life can be ruined.
Shouldn’t we also look at how many people don’t get murdered because they have a gun in their house
There was enough info published in my original citation to derive that.