I'm suspicious of the cheesecake and John Galt potential. I haven't read up on this outside of this thread, but the introduction here sounded a lot like "Hey rich people! How about it?"
I imagine the group is large enough and enough of the funding would be coming from public sources that there would be some filtering to prevent excess cheesecake. I don't think you'd get Paris Hilton naively signing up for a fabulous vacation.
But I do think there would be demographic-related problems.
First, you'd get John Galt wannabes. They may be competent and fit enough to qualify as a productive member, but they'd also be going into it with a shitload of pretentious baggage and something to prove. I'm willing to bet enough people like this would get through to cause serious problems.
Second, and more importantly, the culture shock for these people would be intensely traumatic. These people would all be accustomed to being treated like royalty. The one common factor among almost anyone with $500k down payment in the bank is that every single day of their lives they are surrounded by people poorer than them who are literally begging to be their servants in some capacity. Put 80,000 such people together in an isolated desert wasteland with incredibly limited resources and no one around begging to see to their needs. I would not want to be there, but I would love to watch from a distance.
If this actually happened and produced a stable and friendly community, I would absolutely be on board the first colony expansion ship. I'm just not optimistic about that, even if this unlikely project did ever happen.