Well, the Caribbean does attract some fairly well heeled customers, and for many island holidays - be it Caribbean, Seychelles, Maldives, Mauritius, Bali, or Tahiti, the week you are looking for is the busiest of the year and airlines know they can sell the whole plane at top price. This is therefore what they ask for every seat. It is not a question of 'filling up', yield allows airlines to 'pretend' that only the top bucket is available even if they have only sold two seats on the plane at a given point in time! But essentially, this is most unlikely to change and as long as you want to travel during xmas week and particularly to that destination, fares are likely to remain extremely high. You might end up having slightly lower fares on xmas day itself as some people don't like to travel then but even that is unlikely. You might be better off flying to somewhere in the US meet some of your other family members as more competition than to Curacao might mean a few slightly less expensive options.