One fact remain, many gun used in crime in this world (Not just United States) are obtain illegally, same as almost every case of get away car after a bank robbery is coming from a illegal way. You have to be an idiot to think you can get away with a crime you commit with your own firearm.
You not getting the bigger picture.
If the country's law states "home owners can obtain a fire arm to protect their family and home" - this means that the majority of households will have one.
Example:
US has 10 million people, 9.5mil have guns. Of course, in a house robbery or whatever robbery these guns will be stolen.
UK has 10million also, but only 100,000 have firearms including police. Now since the UK households have very little to no firearms, in a robbery there isnt a fire arm to steal.
Now if the majority of houses have a gun then that increases the chances of that gun being obtained and used, whether illegally or not.
The problem has to be looked from the bigger picture. Not from the smaller spectrum.