It's still, also by many indexes, one of the safest countries in the world, despite the objectively isolated issues you see in the media... Unless you come from another top OECD, coming back doesn't sound like a great deal.
What's your definition of "isolated issue"? Most people use it to mean a random one-off that isn't part of a pattern, which can't reasonably be applied to mass shootings in the US at this point.
Mass shooting and terrorist atacks are still extremely rare events, very much like plane crashes, compared to the many other ways one could get killed or injured.
I agree that mass shootings aren't a large statistical risk for an individual. I'm only objecting to the use of language that suggests they aren't a systemic issue.