It's a very real problem. On longhaul flights, I lock my passport/papers/$ in my carry-on in the overhead so I don't have to worry about someone rifling my belongings while I'm asleep or off to the toilet.

That said, if there's a crash and I emerge with my papers/passport/$, I will be able to call for help, secure lodging, eat, get refills of necessary meds, etc - regardless of where I am in the world.

If I don't have those things, at the very least, I am likely to spend hours, if not days, of being hungry, thirsty, unable to call anyone, secure lodgings, replace meds, etc.

I don't like the available options, but if I'm in a crash like the one in SFO, I'm going to grab my personal item if possible. I suspect many frequent fliers would do the same.