Medicine can be extremely important.
If you are a diabetic, you aren't going to live long if the insulin distribution is impacted. However, insulin isn't the most difficult thing in the world to synthesize if you know some smart people and have a ready source of sheep pancreas.
You'll need salt.
You mentioned food, but if you are just thinking stored food then that's not enough. You'll need seeds for plants that will grow in the area where you are holing up.
If you haven't already started planting nut and fruit trees, get started. Trees take a long time to become productive.
Worry about your neighbors. Worry about the bad ones, and foster relationships today with good ones. Good neighbors are, in many ways, even more important than guns when it comes to protecting your belongings.
Learn some skills. Aside from the obvious ones such as electrical, welding, mechanical and plumbing, consider canning, smoking, distilling, and even odd hobbies like raising bees or growing mushrooms. (Actually, mushrooms aren't very nutritious. But they taste good and your neighbors might value them . . . after a time.)
If there is a collapse, then cities and suburbs will not be safe. And you sure aren't going to be able to grow food if others in the area are starving. That will be a challenge even in rural areas.
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