Why just two armed? That’s the same mindset as 4 squares of tp and 4 rounds to take care of business. At least have enough to completely take care of whatever business and then double that. Triple would be better.
How much is always a difficult question. Why just a .22LR pistol for home defense (not what I have but someone I know well has only that)? Answer - that is what he can handle at his age and health.
Why do I have whatever number of loaded magazines available with my home defense weapon? Answer - that is what I decided on for a combination of reasons. (Okay, that's not really an answer, but I gave it a great deal of thought and chose a reasonable nonzero number.)
Why only two fighter jets? Answer - The difference between zero and two is huge. You need at least two fighters for redundancy and mutual support. More than two starts to add to the cost without a significant expansion of the range of situations that can be handled.
What we had before was like a home-defense shotgun (whether pump or semi, it had to be 12 gauge and in the bedroom) but with ammo only at WalMart. Having that weapon would have made no sense at all. Two ready alert aircraft is more like the home defense situation for most well-armed Freepers. We are ready for a whole lot of possibilities. We'll lose if SWAT comes after us, or a Marine brigade, but we're ready for anything likely or even plausible.