I like the idea of owning an island, except for the whole "being isolated when shit hits the fan" thing that would almost certainly arise.
I have a friend that worked on an island all summer. She would have to get up really early and drive 40 minutes to a boat-transport and then it would take another 30 to get there. It became overwhelming because of the travel time. I think it seemed romantic at first, but eventually the lore wore off. That said, had she owned the island I think the lore would still be firmly in place. I think it's a worthwhile dream to have. Why not?
If it were a large enough island, I think it'd be great to own an island with a friend or friends as long as we could somehow ensure that money would never be an issue. A friend of mine was throwing around the idea of opening a dive shop and a little hotel somewhere in the Pacific for a while. If I'm ever financially successful enough to do that, I just might see if he's still interested.