Yes, because the US is doing so well with guns, right?
And you're wrong about Switzerland, by the way. Their gun ownership percentages are only around 30% (still relatively high, but definitely not "every advlt"), and only men between the ages of 20 and 30 are conscripted into the military and thus have a military obligation to keep their guns in their home. In addition, the reason stuff like this doesn't happen in Switzerland has nothing to do with the fact that "everyone has guns, derp", but more with the fact that Switzerland is a prosperous nation with neutral international politics and little corruption. They've arranged things well. And Switzerland isn't even the safest country in the world, they have "low to middling" rates of crime. The safest country in the world is considered to be Iceland, at the moment (according to the Global Peace Index), and they have relatively regulated gun control there. Switzerland ranks fifth on this list, which isn't bad, but it does rank after a few other nations with more strict gun control.
Guns have nothing to do with it.