Fire,violence killings, Those who prep and do not take into account outcome that includes needs for defense are doomed. Without supplies for years and away after to keep on going with fresh supplies starvation and disease will claim you. Being in city will be most risky being far away has other risks, Without friends and family that number 10+ adults survival will be even tougher.
Without water readily available will be main problem anywhere but in cities with nearly no surface water ……you don’t really have to say more do you?
Then comes skills without those even the best gear is useless. Without will to use them it is also useless.
After all is said and done ask how do i survive the guilt of making it, those who have been there know this is an issue too.