The swampland is more of an exaggeration for the way people talk about why they don't want to move to SF, as if the cost of rent is the only reason one lives anywhere. And the San Andreas thing is another common fear I hear a lot and have myself. But why should something like fear stop one from living anywhere?
I live in SF. I commonly hear things from people in Chicago where I'm from like "yeah but I'm paying $400 for an apartment in Logan Square(which isn't true any more obvi)" or "yeah but you have to worry about deadly earthquakes". It gets kind of old because I didn't move out here to pay cheap rent nor did I move our here to wait for an earthquake to kill me.