Profit margins equal jobs, equal stability, equal less crime. I think it would be a pretty selfish choice to throw a whole country into distress in order to save the land that will likely be under the sea regardless of actions taken. Especially being that the low number of people can be relocated.
The problem of applying a cost-benefit analysis to global warming is that it relates to a complex system and is highly non-linear. In situations like this, the limitations of human knowledge make us unable to make accurate predictions.
Even if there is a small chance that Global warming is man made, it still makes sense to assume that it is man made and do everything in our powers to stop it. The cost of being wrong is too great given the limitations in our knowledge.
Also don't forget that the sea isn't only going to rise in area just around the Islands, a couple of meters is going to have very bad effects in coastal regions and cities all over the world. These effects will be disproportionately harmful in poorer countries, but will also negatively affect richer countries too.
You are only looking at costs now as if they were 'wasted' money. Costs now are not waste if you consider that they might save exponentially more money in the future. Negative effects now might save exponentially worse negative effects in the future.
Global warming doesn't need to be fact before you start acting, it needs to be a possibility. Even a relatively small possibility or a few % would make it worthwhile given the costs of being wrong.
Continue investing and supporting solar energy and wind farms. The big problem is that this kind of technology (solar especially) is not financially accessible to consumers. Working to make this more affordable would help lessen the carbon footprint.
It is expensive
because it isn't widely used. If it was widely used the cost would plummet (think computer technology). You don't say 'we will start using it
when it becomes cheaper', you start using it
so it becomes cheaper.