By SHTF, do you mean society goes to anarchy? Because that would kill a lot of people who cannot get to their HIV mess every 4 to 6 hours anymore.
Not necessarily anarchy, a government move to systematically eliminate Christians and conservatives by violent force would be a SHTF moment too.
It basically means a situation where the old rules no longer apply.
Not quite anarchy, but a place where a substantial amount of government largesse is going to have to be replaced with self-sufficiency. Survival will depend on being useful and resourceful, not fabulous.