Most of these properties are owned by the 1% ~ or their friends. For most everyone really close to the Atlantic their beach houses are throw-aways.
Up the coast in Rhode Island there are mansions on/near the shoreline which their owners call "Huts".
For a variety of reasons many of the older properties on the Jersey shore are really old ~ just totally nasty too ~ and still they refuse to burn or fall in. I suspect they are constructed from oak soaked in pine tar for decades.
There are "regular" houses on Gaveston Island (Galveston has a seawall that doesn't work in a hurricane) but the beach communities are mostly houses on stilts and the new regulations are even higher stilts.