You do realize that phrases like "trained people" "killing spree" and "disturbed veteran turning his (weapon) on Chris Kyle" don't exactly buttress whatever convoluted point you're attempting to make, right? You're actually (unintentionally) making the case for stricter gun laws and psychological testing of applicants. Not to mention standing the whole "good guy with a gun" theory on it's ear. The guy who killed Kyle was a "good guy with a gun" in every sense of the word, until he wasn't...
As to Switzerland... This video from Daily Show is illuminating, even though Kosta interjects humor into the equation. And it's 3 yrs old, so since this report was posted in Dec 2018, the US has had close to 100 school shootings. There were almost 30 in 2019 alone, and we're on a similar pace in 2022...
And despite what GOP politicians try and claim about "American society" being the problem, the Swiss have the same sort of societal issues as what Pub politicians try to claim are uniquely "American". For example, 5 of the Top 10 highest cities for cocaine use in Europe are in Switzerland...