First,
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Second, at least you used the letters "IMO" to qualify your statement about the house not being in immediate danger. It's your opinion but it may not be an accurate one. ASSUMING your house is not in immediate danger of burning down, would you forgo buying insurance? My point is that the words "immediate danger" is very subjective. A tropical storm may not threaten him... a category 4 would wipe him (and many others without retaining walls) out from undermining.
Third, talking about "shored up by adding sand"... do you think this will protect these homes if another Dennis hits now during the beach's current weakened state? I'm not sure why you mentioned this in the scope of this discussion.
Fourth, you said that no other seawalls have been built in the area. Are you suggesting that if your neighbor elects to go down their ship (by not installing their own retaining walls), that you should as well? I'm just trying to understand your logic.
Do you own property in the area? A little perspective would help us understand your position. Thanks.