Switzerland is a bad comparison. Guns are strictly controlled there, despite the ability to own guns. People are not buying, owning and stockpiling weapons without the knowledge of the government. There is no comparison with the US, where gun ownership is a free-for-all and nobody has to prove he even knows the first thing about using one. If the US were to even suggest putting into place the controls that Switzerland has on gun ownership the NRA and the US gun nuts would have apoplexy. If you want a good rxample of strict government gun control, look no further than Switzerland. For one thing, all guns and gun owners are registered with the government.
That's a good point, but my main point still stands: Gun ownership is still highly common among regular citizens in Switzerland. This serves as a strong natural deterrent against crime.
Most criminals do NOT want a gunfight. They just want an easy job. The knowledge that the potential victim could be packing high firepower will easily make one think twice. I know that from personal experience too.