I enjoyed your commentary, and agree with many of your observations. One guy that comes to mind as an exception is Larry Ellison, who -- whether you personally like the guy or not -- has real sailing credentials.
One other point is that some of these guys aren't as "liquid" (forgive the pun) as you might think. Much of their net worth is derived and calculated based on stock that they own, even future options. If their stock tumbles in value (see e.g. Bear Stearns) so do their personal fortunes. I wouldn't be surprised if many megayachts were not purchased with cash but instead were collateralized by shares rather than the vessel itself -- which could lead to margin calls if the stock tumbles. I guess this is what Giu was implying in his thread title.
The stern of Artemis is growing on me. Do you have any other photos showing the boat in profile, etc ?
P.S. Here are some more reasonable options:
A more manageable size, but built in 1949!? -- 1949 MEGA SAILING YACHT S/711039 Boat For Sale
At least this one is brand new -- 2008 Bloemsma Classic Schooner Boat For Sale