Of course there are those who take things to extremes, but I do think there is a legitimate side to being prepared for "SHTF" events, even though they are few and far between. Events like the LA Riots, Katrina, and the tornadoes in Alabama are things that do happen and people should be prepared for. For example after the tornadoes last year, a town about an hour north of me was put under a sundown to sunrise curfew with the National Guard in combat gear on the streets to try and deal with looting.
Now things like this don't require 500 different guns and sniper rifles with 25,000 rounds of ammo for each, but I don't think that one or two ARs, AKs, or FALs (depending on your preference) is a bad thing. A few concealable pistols here or there is also a good idea as well. Hell, how many people here espouse the merits of the 5.56/.223 round for home defense? Most guns chambered for that round fall in the AR category.
Ammo wise, I agree, don't hoard ammo that you won't use. Then again, if I'm routinely taking shooting classes where it is expected to shoot 1,000-1,500 rounds throughout the course of the multi day class, having say, 5,000 rounds at home means you don't have to go out and buy ammo right before the class adding $200-300 to the total price of the class. Or if you're a competitive shooter who goes through 250 rounds per range trip and go to the range 3 or more times a week, having a good stock of ammo at home means you don't have to go out and buy ammo every week (and lets you take advantage of volume discounts).
I think its pretty stupid for someone to buy a gun for "strictly SHTF" and never take it out to use and play/train with. If you don't practice using it and know how to use it effectively, its going to be useless. The knock off aimpoint might fail after 3 days, or some other part of your gear may fail. An emergency is not the time to be realizing "I have no clue how to do this". (I'm a firm believer in training with your weapons every chance you can get if you can't tell
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