I like Tim Pool's suggestion that a lot of things could happen so you should be prepared for the things that could be most likely. Lack of food and water and medical supplies is a really easy one to take care of quickly, there's also a danger of freezing to death or overheating in much of the world. If you've got those basic biological essentials taken care of for a couple weeks you can hunker down in an emergency and let things cool off no matter if the issue is war, disease, or the greatest threat since WWII, people publicly disagreeing with the leader of your country slightly.

For probably $100, you can have enough basics tucked away that it doesn't matter what happens. And if basic essentials aren't going to be enough, odds are you're not going to be able to prepare enough to survive anyway.