The most fundamental lesson for preppers: when disaster hits (and before a disaster hits if people are warned that said disaster is coming) whatever the average person needs to do to prepare, you can bet that all 50,000/100,000/2.5 million people in your city will be doing the same thing. You need groceries for a storm heading your way? You can bet that most people in your city will need to do the same thing. You need gas to be able to evacuate ahead of a hurricane? You can bet that most people in your city will need to get the same thing. You need a fan or an air conditioner because your city is experiencing a heat wave? Yep, everyone else will have the same need.
As a prepper, there should be no need for you to fight your way through the hordes to get the survival supplies you need. You will have prepared way ahead of time, and be chillin on the couch watching the news showing the masses fighting over the last roll of toilet paper at your local store.
Exhibit A Exhibit B