It all comes down to motivation. While I understand questioning having a 401k.. (I don't have one) and other earthly treasures that take away our focus on obtaining our treasures in heaven, there is another side. I believe the Lord leads some people to stock up on food, etc. Its not as much as a self survival thing as it is that I want to be able to help others nearby (primarily unsaved friends and neighbors) if things go south and they can't get food. I see it as a witnessing and serving opportunity.
If the Lord leads some to stock up for something coming down the pike, its not a failure of faith as many of you would lead some to believe. He DOES provide for our needs and I've seen Him provide in some very unexpected and awesome ways for us. And many times He provides for our needs through other believers who are listening to the Holy Spirit.
So it, like so many other things, comes down to the motivation in our hearts and "why" we are doing something. If we stock up out of fear and lack of faith or trust, that is wrong. But if we stock up because we feel led to and its, not out of fear, but the possibility of being there to help others, then that's ok too. Don't automatically assume a believer is operating out of fear and lack of trust if they discuss stocking up on the basics. That well may not be the case.
ps. And stocking up on ammo isn't a bad thing for self protection. Especially for some of us who live in areas where wild animals aren't the only things roaming around. Wisdom is a needed asset in every situation and doesn't show a lack of faith or trust in the Lord either.
"Those who hope in the LORD will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and not be faint."Isaiah 40:31