This would be a failed idea because the sand would never get assimilated by the tectonic plates. The water current would eventually weaken the structure because its not in harmony with nature. Where have you seen a structure carved out by nature in shape of a palm tree? The marine life is already suffering and this would create a geological imbalance as well. How well are they prepared to deal with a Tsunami would be very interesting to know because even if the island is left vacant, what about the debris that would come along with Tsunami water? It would hit twice as hard as the water itself. This Island might generate a lot of money but it would be a time bomb like a sleeping dragon. The erosion of the shore would be another master affect and local people would suffer it.