Black Swan or Migrating Bevy?

A “black swan event” is random and unexpected.  Popularized by Nassim Taleb in his book “The Black Swan,” which describes an event (such as the last economic meltdown) as an unpredictable event.  I ask, are the repeat real estate crises of every 10-12 years unpredictable, or a bevy of black swans migrating in wedge formation? […]