Many of these people are already evacuating the island. Avoiding the rush is a very smart thing. When it is neccesary for people to evacuate, the water taxi does not charge a fee or charges very little. The airlines also cuts their rates by about 90% in the event the island needs to be evacuated. I remember for Wilma, there was a line up at tropic air all the way down to Monchos.
Thankfully, we are not at this stage yet and all the computer models now show it going north but still too soon to let our guard down.