Well . . . I’ve lived here in the woods for a long time now. In the past 30 years, an earthquake destroyed our house, we evacuated for a large fire that came within a few miles before being stopped, and a 500 year flood that isolated us for a week or so. Among other things.
I don’t have a bug out bag. I have never wished for a bug out bag. For these particular crises, common on the west coast, here is my experience:
Earthquake: you will virtually certainly not be injured or dead, and all your stuff will be right there. Just a bit messier than before. Okay, astonishingly, unbelievably more messy. In our case, it was just like our house was picked up by a giant and shaken like snowglobe and then carelessly dropped. You will probably not have electricity, gas, or water. Keeping a food-grade barrel of water lashed to something anchored to ground is not a bad idea. You will not want to leave, you will want to start cleaning up.
Fire: at least for a wildfire, if you are at all proactive you will have many hours to pack up and get out. If you are stupid and stubborn you can wait until the firefighters arrive and give you ten minutes. Then, yeah, a bug out bag might be good, although you are just driving to a hotel, or worst case, a school gym set up with cots.
Flood: your power will go off and you might not be able to leave your house for awhile, so lay in some battery lanterns and some board games. Also the drinking water thing. My sister lives on the Russian River, but on high ground (on low ground the houses are built on stilts), and every few years she has to kayak to the store for a day or two. If you are in a flood plain or on the beach, my advice is move. A bug out bag won’t save your ass.
As for dirty bombs etc., those are fantasies. Anybody forget we have a military capacity something like 1000 times bigger than any other country’s? Still not feeling safe, huh? That’s a problem no bag is going to solve.