More reason we cannot let them take our guns away, we need to get them to the street lights before they kill us off en masse.
Which brings us to the $100 question. Why haven't they killed us off in mass already?
A) They are toying with us because torturing us and subjugating us brings them more power and pleasure before the actual kill
B) They lack the right contagion or the means to appropriately target it.
C) There are external threats and factors from other players ( China, Russia) preventing that action through threats of mutual destruction (China isn't willing to have 98% of their population die )
D) They think they have enough\more time and the ability to conquer us by more conventional means and that would lead to a "better" result
E) They really can't stomach it and need the thin veneer of legitimacy to soothe their egos ( i.e. there are limits to their ability for self-delusion
Any other possibilities?