Survival, through and after any catastrophe, is a numbers game - Do I have enough food & water? Am I far enough away from the worst of things? Do I know enough to survive?
The most common mistakes most people make (in looking at the end of the world) are mathematical. The biggest one is - Do I have enough people around me to ensure that a group of us can get through most of the trouble that could be thrown at us? No one person can know everything that needs to be known, no single person could do all the tasks that are needed to be done.
Of course, bring up the concept of The End Of The World As We Know It (TEOTWAEKI, hardly an acronym that rolls of the end of the tongue) with a group of people, most will think you're mad or joking, some will have their own plans, and very few (if any) will want to combine their plans with yours - and give you both a better chance.
Which brings the other problem - how can I afford all the things that will be needed? There's an adage when it comes to keeping horses - it's not much more expensive to have two than it is to have one. Apart from the fact that horses are social animals, there are a whole range of costs (veterinarians, farriers) where a sizable part of the expense is calling them out - the cost of dealing with a second animal is much less significant.
In human terms, suppose you have an axe, and a hoe. A single person could do a day's work cutting trees for fuel, another day tending a garden. But - two people don't need that much more firewood than one does, the additional time needed to tend the garden is much less significant, especially the rare times a second pair of hands would be needed. And you still need to buy an axe, and other good quality gardening equipment - no point getting cheap stuff that falls apart after the third use. Costs decrease as population increases. To a certain extent.
The other reason is that it's a pain to try to perform surgery on yourself.
Can you blame me for thinking mathematically, when most of my studies are in engineering and science? Although, I dare say that my chemistry would get the most use after The End.
But back to the problem.
Survivalists, as a group, tend to be fairly quiet, prefer operating in family groups (at largest), and somewhat paranoid (they could argue there reasons to be sensible) - hardly the people to congregate in a community. Mundanes (aka Sheeple, ie the people Survivalists look down upon, which is most others) simply don't see the need to worry - after all, It's All Right, Everything's Perfectly Fine. So convincing people of a need to make a few changes to their lifestyle is difficult, particularly when they think Unemployed, Inner City life preferable to Unemployed (but doing Farm Hand type work) Semi-Rural life.
So, the few of us who seem to occupy the middle ground do what we can. Make what we can, learn what we can. And try to make the numbers add up.