On an individual, or family level, it comes down to cost effectiveness. It is insanely simple to prepare for fairly routine mishaps and become self-sufficient for 72 hours. It isn't even that difficult to become OK for seven days or so. People who contemplate a year or so of independence are going to be investing significant resources in their preps. Draw the line wherever you desire.

For me, a big time disaster essentially means I get to go on an impromptu camping trip, using all the stuff I have accumulated over a lifetime spent in the outdoors one way or another.

Analyze the hazards pertinent to your locale (I need to prep for earthquakes, but not tornadoes or hurricanes), and allot your resources accordingly.

Getting government entities to address disaster preparedness rationally is a whole different problem, but one wonders if some percentage of our mammoth defense budget could not be shifted toward disasters and the repair/upgrading of infrastructure...