Why do the countries that do well in the America’s Cup do so poorly in the Olympics?

Here is the final medal table for the 2008 Olympic Sailing Regatta. The thing that struck me about is that the countries that lead in the America's Cup - Switzerland, USA and NZ - did so poorly as compared with countries that have either not taken part in the AC for several years or have not been a competitive force in this competition. Why is this? Money? Maybe but that can't be the whole story. The US has lots of it. I would love to hear what anyone thinks about this.