It was some time in the 90's when we were berthed next to the 187' Feadship. We got to know some of the crew fairly well, although they were tight lipped about the owner. They were on their way from Alaska to New Zealand, and were berthed in Sausalito to give the crew some shore leave.
The boat gets moved to a different part of the world, just in case the owner decides to invite some folks aboard for dinner. The owner flies to the destination, and s/he might not even invite someone aboard. The crew then waits for orders to move to the next place.
Can't recall the fuel consumption, but we guestimated an annual budget of $7-8M for this boat at that time (the 90's), given various pieces of data we could extract from the crew.
Oops, forgot to mention there was a fulltime crew of 13, including the Captain, two chefs and two engineers.
Scale all this up for a 500+ foot boat.