Better yet, they break into your house while you're not there and help themselves to your guns. If you don't have them in the house, fewer will end up on the streets in the hands of those who could not access them through legal avenues.
My pistol doesn't stay in my house, it leaves when I do. The same goes for most of my friends. Living in a state with right to carry laws, leaving a gun at home kind of defeats the whole purpose. In addition, there are preventative ways to secure guns that are left at home. Most of the people I know that have multiple guns for hunting, etc. keep them in a gun safe.
In my view, the problem isn't with the gun owner that leaves a gun out that can be stolen if someone breaks into their house. The problem is that they have to lock all their valuables up in their own house to keep them from getting stolen when someone breaks in.
Criminals will be criminals regardless of the law. The only way to effectively stop that is to make the punishment enough of a deterrent that the crime is no longer worthwhile.