This whole region is flood plain, so very low lying, and the more new housing they build here the worse the winter floods get in general.
For the coastline in particular, just a small hop west of there is (or was) Climping beach, which is now closed as it's been so badly eroded and pretty much all gone. The shingle bank works pretty well as a sea defence, but the areas in front of private properties aren't managed as much as the town beaches. Pagham beach to the west of Bognor is another example of severe erosion, and the properties there are really vulnerable. Then there's the fact your property gets a lot more wear and tear from the elements when you're by the sea.
Having said that, the whole stretch of coastline is packed with massive mansions and private estates. So maybe if you have that much cash you can afford the risk!
Tbh, living not too far away, I'd still snap that house right up!