The Pareto principle (also known as the 80-20 rule, the law of the vital few, and the principle of factor sparsity) states that, for many events, roughly 80% of the effects come from 20% of the causes.Wikipedia
If you choose your preparations carefully they will provide most of your needs without overwhelming your budget and storage space. For example of the man-made disasters the one getting the most attention right now is the EMP. A rogue state or terrorist group detonating a nuke 300 km over the continental US could destroy most or all of our electrical infrastructure. It would take a long time to rebuild the infrastructure because there would be a large number of burnt out parts that would need to be imported and replaced.
If you had a supply of food, a way to filter water and extra clothes you would be able to survive for some time. Add in seeds, a garden and the proper tools and you may be able to survive indefinitely. Some people react to this by moving to a farm which is certainly a valid thing to do but if nothing happens there is a lot of lost opportunity costs that go with it.
I would rather go with small but significant lifestyle additions rather then wholesale lifestyle change on the off chance of something massive happening to the whole world, when there is a greater likelihood of something far smaller but potentially devastating happening to just our family.
