Simply put, the clients thought they could make money over the 25-year term of the lease. The land was close in to the city, so they expected a good location would provide good traffic. They never would have pulled the trigger on buying the land, and the landowner never would have sold it, because it was inevitable that someday the real estate would have higher value for other uses. It's possible that the landowner might extend the lease for a few years, if the commercial development market there is soft right now.
This was not uncommon in the Southeast at that time. Several of the courses on the north side of Myrtle Beach were done on a 25-year lease, including Oyster Bay and Marsh Harbour, which made a LOT of money in their lifetimes. I don't know if either one is still open -- those leases ran out in 2008-2010.
However, it was not a great experience working on that project, because they weren't motivated by the same factors that many of my other clients have been -- it was much more mercenary of a project because of the tight time frame.