The groups and communities that weathered the collapse of the Roman Empire the best were those with some degree of self-sufficiency and military protection.
Prepper has become an umbrella term that is applied to a huge variety of people and mostly as a pejorative based on the sensationalization in media.
Many people that would be dismissed as preppers are perfectly normal people who approach the problem rationally. They take a layered approach which involves preparing for a range of timespans and events from the most basic like an extended power outage of 1 to 2 days or an unusually heavy snowstorm or minor flooding that may temporarily make roads impassible. Then escalating to natural disasters with week or monthlong power outage, gas and food shortages and damage to infrastructure. Personal disasters such as a housefire, flood or even financial difficulty from loss of job or health crisis. Then larger natural disasters like hurricanes, tornadoes, earthquakes and forest fires. Only after those are sufficiently covered would they consider more speculative events such as extended nationwide financial crisis, large regional disasters like a volcanic eruption, extreme earthquake, tsunami, major civil disruption, war, economic collapse, government coup, pandemic, etc.
What they do to prepare would include basic individual preparedness like having a generator and electrical hookup to power their home, extra water and food, essential everyday medications, alternate heat source, emergency radio, enough gasoline on hand for both the generator and vehicles and equipment like a chainsaw for clearing downed trees. Also vehicle packages or "go bags" with what you would need should you have to leave your house immediately during an evacuation or fire, if these are kept in the vehicle then they also help should you become stranded in your vehicle during a snowstorm or breakdown. They also prepare in their community often by simply having good relations with their neighbors and helping them when they're in need but may also volunteer with local emergency services or be involved in charitable groups or with likeminded people.
A lot of this has a long history in rural communities that required some level of self-sufficiency due to a lack of services, more precarious roads/powerlines and being low priority for aid during disasters.
FEMA's recommendations only address short term problems and evacuation. They're not sufficient for disruptions lasting longer than a week and the difficulties that people face in more rural areas during disasters.
I've personally been through events that have cut off grid power and transportation for my area for a few days as well as large widespread power outages lasting more than a week. When that happens you find out very quickly how important it is to prepare ahead of time.
Disasters are rare but not rare enough that you can be certain you'll never experience one first hand. "Collapse" events are very low probability, low enough that most people in the world won't likely experience one in their lifetimes but they do happen, you can probably name several countries that have recently been through such events due to war and many more that have been through them in the last 100 years. Many of us are lucky to live in very stable nations so you don't need to make those scenarios your number one priority but it's at least worth the effort to consider what you should do now to help yourself and your community to continue to thrive over the long term.