It's not a matter of smarts or money. It's just about being disciplined.

You build up emergency supplies ALL THE TIME. Just buy like one or two items more than usually do and then put them away in storage. It also helps to have a spreadsheet or something to track expiration dates.

If you have items that are expiring soon, use them and then replace with new.

The poorer folks, as you described, are exactly the ones who should be doing this. They're the most impacted when shortages occur.