This group stresses being able to stay alive for indefinite periods in life-threatening wilderness scenarios, including plane crashes, shipwrecks, and being lost in the woods. Concerns are: thirst, hunger, climate, terrain, health, stress, and fear. The rule of 3 is often emphasized as common practice for wilderness survival. The rule states that a human can survive: 3 minutes without air, 3 hours without shelter, 3 days without water, 3 weeks without food. 
In 1980, John Pugsley published the book The Alpha Strategy. It was on The New York Times Best Seller list for nine weeks in 1981. After 28 years in circulation, The Alpha Strategy remains popular with survivalists, and is considered a standard reference on stocking food and household supplies as a hedge against inflation and future shortages.
People who carefully and painstakingly prepare for mass extinction don't exactly seem like the type of people who plan great parties. At least, with those vast collections of guns, ammo, and other terrifying armaments, I certainly hope not. Then again, I suppose everyone will need a drink or 10 to get through the inevitable horrors of forever navigating the "what's for dinner" question without Seamless or, you know, realizing that your urban-dwelling family members will probably never arise from the blasted pit of rubble where their apartments once stood.
It turns out that when you're down to your last moldy hunk of bread and giardia-laced mud puddle, letting it all melt away in a cloud of smoke for a few precious moments can mean the difference between giving up and giving the rat (eating) race another go. If history has anything to say, it's more common than you think for people to happily give up MREs and gunlord harems in return for hastening their ends with carcinogens wrapped up in tidy paper packages. In traumatic situations like war, cancer sticks are often valued more highly than food. Even in the current (more or less) pre-apocalyptic global economy, cigarettes are one of the stable forms of currency.
While survivalists accept the long-term viability of Western civilization, they learn principles and techniques needed for surviving life-threatening situations that can occur at any time and place. They prepare for such calamities that could result in physical harm or requiring immediate attention or defense from threats. These disasters could be biotic or abiotic. Survivalists combat disasters by attempting to prevent and mitigate damage caused by these factors.