What sort of mental illness are we talking about? Do they think that the queen is a lizard and the government is putting chemicals in contrails? I really don'

What sort of mental illness are we talking about? Do they think that the queen is a lizard and the government is putting chemicals in contrails? I really don't care if they have a gun. Lizard and chemtrail people are clearly loony, but they seem perfectly harmless. Instead are they a psychopath fascinated with violence? In that case yeah, I am not comfortable with them having a gun... but if we know who they are then why the hell are they not institutionalized already, rendering the issue moot?