I don’t really see this. If the stock market were to suddenly change to a situation where increases and decreases were much smaller than before, or to a situation where they were more predictable and less likely to change directions, that would put all your probability estimates up in the air, but would have decreased volatility.

How do you know that volatility is coming along? Sure, of the options I stated, the most likely were the most volatile. But of all the things that could count as a black swan, why are you confident that volatility will be a feature of the most likely?
(note: I agree with you, that would be my feeling too. But are our feelings based on anything rational? Or are they just a failure of imagination?).

Not quite to that extent, but close. For a few days after, I felt the world was going to change – had no idea what to expect from the point of view of air-travel security, terrorism, the economy, international relations, even the future of the world.

Of course, I was more impressionable back then. I think that the stock market spelling out the Koran, today, would have only a slighter greater effect than 9/11 did then.

Time travel (and personal contact with a time traveler) is sufficiently unlikely

Yes, that’s the easy way out. But you get round that by adding sufficient evidence the story to convince yourself that Time Travel is possible. In fact, Time Travel isn’t needed – you can replace it with an equivalent situation – someone with insider information on, say, a huge upcoming scandal. If he/she doesn’t say anything more than that, doesn’t tell you the nature of the scandal or who’s involved, but just hints that it will demolish a lot of your estimates, then the situation is analogous.

You should probably not even be on the look-out for extreme black-swan events to check your experience for confirmation, as confirmation biases are two powerful, and 9/11 level unlikely and significant events are fairly likely in aggregate. Anything unlikely enough to genuinely confirm something as unlikely as time travel to a meaningful degree will be obvious enough that you will notice without needing to be on the lookout, and is likely to be sufficiently surprising that your expectation that money is highly desirable should be, conditional upon such an event, relatively small.