"Preppers" as seen on TV are folks who think they're preparing to survive the end of the world as we know it. Not the Biblical end of the world, but a collapse of society and descent into chaos. While I would never say this is an impossibility, it is extremely unlikely. As I wrote earlier, it is very smart to have a 3-7 day disaster kit, but it is impossible to prepare for the end of the world without totally changing your lifestyle and owning several acres of arable land. For a thorough and decisive refutation of "prepping", read "Alas, Babylon" by Pat Frank. It's an awesome book, an easy and addictive read, and only about 275 pages. So you could put it on your nightstand for a couple of days and have it read.
But for grins, let me take a few pokes at preparing for the apocalypse:
No matter how much canned food and bottled water you have, it isn't enough. Your diet will change drastically and you will contract a potentially fatal case of dysentery. If you live here in the middle of the country, you won't get enough vitamin C in the fall and winter and you will contract a potentially fatal case of scurvy.
If you have large stores of food, people will find out, and they will try to steal from you. That means you will be working hard all day to tend fields, find water, get food, maintain your shelter, then sitting up all night long on watch. Of course you could hire neighbors or trusted friends to do it, but you'll pay them in food stores, and you'll run out of preserved food even faster. Looters will strip major cities of goods in hours, leaving them to scour the small towns and countryside looking for supplies in despair.
If you get sick with anything serious, you will probably die. The average citizen can't go to the pharmacy and order ten year's worth of penicillin, or pain killers, or IV fluid kits. If you get shot, you'll probably die. If you break a bone, you'll either heal improperly and be lame for the remaining years of your life, or die of infection and internal bleeding. Unless your neighbor is a surgeon with a small pharmacy like Doc Gunn in Alas, Babylon.
You need a farm to survive long-term. You'll need about 20 acres, draft animals, olde-tyme farm tools, pigs, chickens, and possibly a couple of dairy cows. Your preserved stores are a band-aid. To survive and perpetuate humanity, you'll need a small farm. And you'll need to guard it night and day. Also, you'll need a water source to water the animals and irrigate the crops during dry times.
You're not going anywhere with all your stuff. Most gas stations are replenished weekly. With no resupply, there will be no more gasoline within hours of the bombs going off (or zombies, or whatever). Remember 9/11? In my tiny hometown there were lines to fill up within hours of the towers going down. You simply can't have enough gasoline to haul you and your stuff to safety if you are within a radioactive area or otherwise need to move. You'll get farther in a Honda Accord with a couple of gas cans in the back than a Hummer with all your canned food.
Gold and silver have never been currency in emergencies. You can't eat it, burn it, or shoot it, and it only has value in a cash economy. Now that there is no political or economic structure, we're back to bartering. You're better off with a case of 22LR than a chest of gold coins. Gold and silver can be economic hedges against inflation in a cash economy, but in the world of bartering, they're going to be worthless until a cash system gets set up again.
Read the book, see that I'm right, and enjoy. Oh, and for the record, I'm "prepping" by contributing to a Roth IRA.