Ideally, you should have your own land where you can grow food, where you can take water from the ground, you should have strategic supplies of clothing and other things necessary for the next 5-10 years. I think that this is quite enough to live well even in such a situation.
This doesn't mean that you need to isolate yourself from society. When you are calm about your position, you can do what you do more effectively to improve the position of other people in the world.