My wife is one of those people. She's been doing it for a few years and I just thought it was funny at first. Now it is something that makes me proud of her. She says it's her contribution to our family since she doesn't work. I have been with her when we go to a store and walk out with a couple carts full of stuff for less than five bucks.
That all said, the Indy area is not "friendly" to extreme couponing like some other metro areas. All the stores I can think of around here limit the customer to either 2 or 4 identical coupons at a whack.
We don't have as big a stockpile as some folks on the TV show, but I don't envision running out of some things in my lifetime