Actually when you consider the global implications of climate and the local effects of shore, a local area using local money to protect local shore in the face of global inaction they are powerless to change makes perfect sense.
It is actually your position which makes no sense. "Hey 4.6 million Louisianans, sure you're only 0.00063% of world population, but protecting yourself and your land from what the other 99.9994% do is futile, you must instead convince the other ~7.1 billion humans to change so your land will be safe!"
And what about moving industry and residences away from the current coastline over the next 50 years? Make a plan to prevent new real estate development within a certain distance of the current coast; plan the obsolescence of currently developed areas and over time reclaim them for the environment.
That's a problem when the coastline is the reason for those industries and residences being there. It's not exactly feasible to relocate the oil refining and shipbuilding industries of New Orleans and Baton Rouge to central Mississippi.
It is actually your position which makes no sense. "Hey 4.6 million Louisianans, sure you're only 0.00063% of world population, but protecting yourself and your land from what the other 99.9994% do is futile, you must instead convince the other ~7.1 billion humans to change so your land will be safe!"