Yet it's still the guns, be it in the hands of an officially mentally ill person or someone who's undiagnosed but can't descern reality from fiction none the less.
Assault weapon ban goes into effect, mass shootings drop drastically.
Assault weapons ban is allowed to expire, it goes up north of 200%.
Assault weapons are revered like Jesus himself and mass murder scenarios suddenly happen every goddamn week.
The prevalence of weapons and free availability of them to virtually anyone, be they mentally ill or fundamentalist radicals, is the direct cause of this getting so out of hand.
Not mental illness or healthcare.
Mental illness exists everywhere.
Mass shootings (and probably any shootings) on the scale and regularity like in the US do not exist anywhere else.