Tropical paradises rarely become centers of commerce. Singapore is one exception to the rule. Most tropical islands become ultra-luxurious, exclusive vacation destinations. Most tropical islands are far removed from civilization and are in remote locations that get little human contact.
Singapore is an exception to the rule for a few reasons, the most important one being its location as the center of Southeast Asia. Singapore was in a prime location to be an airport shipping center and air hub. Singapore is strategically in the center of things.
Furthermore, Singapore has a history of attracting affluent families with high IQ’s and personal wealth. Most cities are the brainchild of a network of well-to-do people who had visions and plans to grow the city into something special. Singapore’s Peranakan history and culture conforms to tat basic principle.
The islands of Seychelles, the Caribbean islands, New Caledonia, Fiji and Sri Lanka are all too far flung and removed from centers of civilization to ever grow into anything of significant commercial importance. Growth their has been tried and unsuccessful. Unlike the mediterranean countries, that are connected with each other through sea routes, these tropical islands were never in a network with each other and never grew to the global importance that Med countries did. India had a substantial civilizing effect on Sri Lanka, Mauritius, and Fiji, but they were still too isolated from the mainland and India lost its influence many many years ago.
People need to be connected with other people in order to learn, grow and experience changes. Isolation kills these things, which is why most tropical islands never grow into economic relevance. However, it is human nature to like islands and tropical weather, so there will always be a demand for tourism to these countries.