It is to them, just not you.
Assumptions. I know people who have timeshares down there. They only get to go once a year if that. I know people who go once a year and stay on property. I can also argue that locals can spend a lot more at WDW than someone only traveling once - more expensive tickets, dining numerous times over the course of a year, attend more upcharge events, etc. You seem to assume that they simply show up, ride some rides, and go home - but I know plenty who do otherwise. They may not spend as much in a single day or a week as someone making the once-a-year trip, but over the course of that year they spend a lot more. So your argument on these points has no merit.