Besides all the benefits that Bourne has listed, there's one more I want to add. Last minute flying.

Imagine if there was an emergency and you needed to fly to a far-away city (say Taipei, for example) on short notice.

For the average person, you'd have the choice of a $1500 coach tickets or $3k for a business class ticket.

For a FF'er, there's the choice of using miles.

The difference is HUGE, and that's when your FF status and accumulated miles pay for themselves.