The Obama-martial law scenario is nuts, but I was very glad for my wife's prepper tendencies when Hurricane Sandy knocked out our power for two weeks. We had plenty of fresh water stored, food packets aplenty, and even milk for our baby. We had propane-powered heat spacers.
Yeah, it comes in handy.
After the Loma Prieta Earthquake (1989), we were glad of our "preps," including 5,000 gallons of water in distributed tanks, generators, chainsaws and rescue equipment, and extensive comm gear. We had five youngsters at our place. Fortunately we were able to get them back to their families by the next morning, though we had to force the roads through a couple of downed trees.
Electricity was out for a month.

So was most telephone service. For the next week we relayed telephone service from the few areas we could still talk to, to points elsewhere in the state, bridging via Ham radio.
After the Northridge Earthquake (1994), I didn't have those kind of resources (having moved into the area not long before), but within ten minutes I was fully loaded and ready to camp it out. Of course, daylight soon made it clear that it was an unusual local M
R 6.7, not a Landers- or Fort Tejon-style M
R 8, so there was no need. I did assist with seismic surveys but the impact was slight this time.
There's a fine line between prepper and prepared. Be prepared, not prepper.
Sure is.
I get a fair amount of "prepper" types in my firearms classes. But there's one prep they all seem to miss, which I tell 'em:
Get to know your neighbors. Stop viewing them as potential zombies and become more involved in your community. Except in the rarest of scenarios, they're the ones who will save your ass -- but only if you find out about each other first.
I think the threat of "preppers" is overblown. There's been paranoiacs forever. Most people aren't, they're just following a trend.