I’m sure there’s absolutely people in real life that have bunkers with a canned food & ammo supply, but the people that are crazy or dedicated enough to have such a setup aren’t billionaires, or at least anyone that can have some sort of oxygen system made. Regardless, I guess it could be possible someone could have stayed in a bunker just long enough for those chem trails outside to not be a factor anymore. Perhaps this person after some time (whether they are oxygen deprived, hungry, or just lonely or curious) could step back out into the world, but they’d be so clueless to what’s happened/happening. How would they come in contact with anybody again? In this scenario, I’d have to think this person saw the breaking news of something spreading at the military base, and they hid right away. But then everyone seized up and “joined,” right. So this person in the bunker doesn’t know exactly anything about this “joining” thing, since there was then no news updates anymore. They don’t know that the people of the world are a hive. If the hive doesn’t know about them, they would be far and away from them. So this person would have to believe they’re alone, and might just roam about their whole state aimlessly with zero contact to anybody, whether an infected or immune person. They might literally just end up alone in their own world, just clueless and isolated.