Thanks for your posting, Jamie - look I've never been to the USA, except for two hours in Niagara, USA in 1969. So I've successfully slandered a whole nation in total lack of personal knowledge. But you know, paranoia is a form of delusional state, it is a form of psychosis. From the first Mayflower pilgrims to the slaughter of the natives to the fear of the descendants of the slaves they brought into the country who might now want to get their own back, to their xenophobia - so even if this paranoias is "mild", it's still significant. And of course, individual Americans are like anyone else, if you prick them do they not bleed? But culturally they are not like anyone else. Perhaps that culture wouldn't matter so much if the country was just the size of Australia, but when it belongs to the most powerful nation on Earth, used to throwing its weight around, that's when we have problems.
These shootings might be domestic affairs, but internationally surely they are reflected in the incessant wars of aggression waged on others? I mean, the attitude to Iran, surely that is to take "revenge" on that nation for defying America for so long, same with Venezuela and many other nations in WW2 history, much as these shooters are often motivated by taking revenge on perceived slights. As you mention, there's an actual love of violence - both as a solution to so many problems, and perhaps even for its own sake?