People actually DO PAY for a FULL J ticket to Europe!
Wow, I actually witnessed this today at the DL BE check-in counter at JFK Terminal 2. The passenger standing next to me while I was checking in had just missed her JFK-FCO flight (where she had gotten a "Z" upgrade) and the agent was trying to rebook her (even though missing the flight was entirely her fault, not DL's). Problem is today (9/16)'s TATL flights are all VERY FULL. JFK-MXP was sold out, as were JFK-VCE, JFK-CDG (for the connection to FCO), while the second JFK-FCO had 1 seat left (J) in BE. The agent offered to rebook her on a JFK-AMS DL flight with an AMS-FCO connection on AZ. When the passenger found out that it had to be in Y, she asked if there were any other flights that had "Z" upgrades available. The agent told her that the only open BE seat anywhere later this evening was that 1 single seat left on the later JFK-FCO flight; she would have to pay the fare difference of about US$3000+. She thought about it for a moment, and then said, "Yes, I'll take it" and whipped out her credit card....so yes, amazingly, there are people who have no qualms about plopping down $3000 one-way for a full J TATL ticket!
Writing from the BE lounge at JFK waiting for my flight to CDG....