Stockpiling to an extent makes sense, in my mind. Things like food and water to last at least a few weeks, ideally months or a year, are quite practical. Because the moment a problem is obvious, it's too late to get them. If you've ever lived in a hurricane area and let your toilet paper supply run low before an event, you'll know what I'm talking about ;) Alternatively, if you've ever been sick and not wanted to leave the house for a week, or lost a job and wanted to limit what you're spending, etc.

Also, stockpiling should be done smart. If fuel doesn't last long, make sure you're using things like fuel extenders to keep them usable. And ideally, make it part of your daily life. Stockpiling 5 or 500 gallons of water in your apartment or house is a great idea (when the water main breaks after an earthquake, would you rather be the person who can help others because you know you're taken care of, or the guy who's fighting off dehydration while he waits for the red cross to arrive?), but keep using it. Don't buy one of those blue tanks and just leave it in a corner, buy 10 and use them, replacing them as you use them. Same thing with food, and fuel.

Going to extremes, of course, give you diminishing returns (like anything). So stockpiling several million rounds of ammunition and more medicine than can be used before it expires doesn't make much sense.