If you think about all the disastrous events that have happened in the life of a currently elderly person, you have to come to the conclusion that within your lifetime you stand a good chance of being caught in a disaster. Who knows what that might be - a hurricane, a flood, a massive urban fire, a nuclear attack, a terrorist's dirty bomb - it doesn't really matter. In your lifetime, you could very well experience a disaster. And technology has made us susceptible to a wide variety of new and devastating disasters, from massive power outages to biological warfare agents. However, the problem facing us, now more than ever before, is a triple whammy of the ever-diminishing need to build skills for self reliance in everyday life, how well humans conquer nature, and the exploding population density.
Just a few generations ago, things that we now consider "wilderness/disaster survival skills" were just parts of everyday life. You constantly needed to build a fire, slaughter and prepare animals, grow vegetables, build and repair things, travel for days to reach destinations less than a 100 miles away, defend against wildlife and criminals, use a knife and edged tools, and generally take care of yourself and others without the benefit of just buying a solution to your problems. Now, we live luxurious lives, and can live out our entire lives without needing to do any of those things. We turn on the electric stove, to cook meat and vegetables we bought in a store, throw things out when they are broken, can drive across the continent in a couple days (or fly in hours), and live in homes safe from most wildlife and protected from criminals with security systems and police forces.
Many people don't think at all about surviving a disaster. It's not unexpected, considering that we live day to day so far removed from any of the dangers associated with catastrophic events. "Out of sight, out of mind." It's always going to happen to somebody else, and in the back of our minds, we're just so used to being able to go to the store and get what we need. But living in a disaster situation is a completely different game, because some or all of the infrastructure that we build our lives around - electricity, potable running water, police protection, a ready supply of gasoline, phones, 911, etc. - will quickly disappear in an emergency. Maintaining a set of survival skills and supplies that can support you without any of those common utilities and conveniences is a challenge.
Human beings are unquestionably the most awesome animal on the planet. Despite being weaker than even small animals - people are even easily injured or killed by dogs - our brains make up for it in spades. We can do ridiculously awesome things, like send people to the ocean floor or surface of the moon, dig gigantic strip mine pits, build mile-high skyscrapers, change the course of rivers. We bend our environment to our will, at every opportunity, and we build the tools needed to make it happen. We've gotten used to how powerful we are, and we are now able to live in such densely populated cities because we can create and transport food and resources so efficiently. While people used to have to remain spread out to a degree that allowed them to produce their own food and materials, we can now produce them super-efficiently elsewhere and then bring them to wherever we are using fantastic logistics systems. Many types of disasters will extremely adversely impact our ability to bring the resources needed to support life into urban and suburban areas. There are just more mouths to feed than the urban environment can sustain.
The kicker is that as time goes on, and the population increases, more and more areas become densely populated urban areas. The most disaster-vulnerable type of area for people to be in becomes the rule instead of the exception. This also means that any given random catastrophic event has a greater chance of striking an urban area, not to mention deliberately urban-targeted things like terrorist attacks.
The combination of these three thing creates a particularly nasty side effect, that turns an urban disaster area into a cage-fight for survival. What happens when a disaster strikes a densely populated city, shutting down utilities and the constant influx of food? Chaos. Those that were not prepared ahead of time are in a scramble. They have to get to a store to get as much food as they can, but so does everyone else. They have to fill their vehicle with gas (that they've probably been putting in $5 at a time for the last year), but so does everyone else. They need to get water from the local stream/pond, but so does everyone else. Our ability to artificially support such an unnaturally dense population has created a huge vulnerability. Only so many people are going to actually get food, water, and gas, before there is no more to be had. The roads will be jammed by the accidents and breakdowns of literally millions of people attempting to flee the disaster area.
And that's the good part! What happens when people get desperate, because they have no food or water? Understandably, they get violent. If you have what they need to survive, they will try to take it from you. Looting, violent mobs, and rogue gangs quickly crop up, in addition to normal people driven to desperate measures. Personal security just became an important bullet point on your survival list.
Certain types of disasters, especially fast-acting ones that physically make areas uninhabitable, like flash floods and nuclear attacks are particularly troubling for survivors and those in surrounding areas. With people physically displaced from their homes, with little or no warning to allow preparations, they have little or no means to support themselves, and also must travel out away from the disaster area. This pushes refuges out into surrounding suburban areas, that are already stressed themselves by the collapse of utility infrastructure and the lesser effects of the disaster at that range. People displaced from their homes and desperate, are pitted against people desperately trying to hold on to what they do have left. This immediate social degeneration may be the greatest problem, in such a worst-case scenario. Maintaining physical security of an area is not something most people are prepared or trained enough to do, except for former military personnel (especially combat-arms professions). If the disaster is severe enough, widespread, or a coordinated attack on multiple areas or cities, the infrastructure collapse would likely spread to military, law enforcement, and other "first responders" too. Also, in the end, even military and law enforcement personnel are people too, and may break ranks to take care of their own families and friends.
It gets pretty scary when you role-play it all out like that. And the only real solution is to be prepared ahead of time. Ideally, we would need to be prepared to live unassisted in-place for a decently lengthy period of time - possibly a couple months. At a minimum, we would need to be prepared to weather the initial wave of chaos - survival experts recommend 3 days or more. That means storing sufficient quantities of water and food, as well as maintaining sufficient means to fortify and defend yourself. Defenses could be as simple as a handgun and rifle, or as complex as keeping a supply of sandbags and concertina wire.
It's unfortunate that it seems these days being prepared is socially unacceptable. You either have those that naively remain completely unprepared, or those seen as "conspiracy theorists" who are eagerly preparing for armageddon. I could just imagine the response I would get if I told people of plans to have three months worth of food in my basement, or a bag constantly packed with 72-hours of emergency supplies. It would be nice if we could turn that attitude around to a positive one.
One fun way that people have been putting a positive spin on preparedness is with humor. Groups have been springing up that market themselves as being prepared for a "zombie apocalypse", such as Zombie Attack Prevention (Z.A.P.) and the Zombie Preparedness Initiative. On the surface, that seems pretty nutty, but really they don't believe their own propaganda. They operate under the principle that if you are prepared to survive a zombie invasion, you're probably ready to survive most other disaster scenarios. They stockpile supplies, prepare survival plans, practice survival skills, train with weapons and equipment, and seem to have fun doing it. I guess they'll have the last laugh when, not if, a disaster finally happens.