I think the $ in wakeboarding comes down to the nature of wakeboarding vs skiing and the $ the average wakeboarding joe will drop on equipment and boating accessories. Those who know wakeboarders (of which I tried to be one before realizing I don't really enjoy wakeboarding) know the guy who spends big buck on a big boat then turns around and drops another 15k on stereo, underwater lights, upgraded ballast etc all with the goal of having that boat that everybody wants to hang out on. He might not be able to do anything cool on a wakeboard but if his boat is big enough he might get somebody in his crew that can do some cool stunts, and somehow that makes himself feel cooler. There's a lot of one-upsmanship that translates into more $ spent and eventually into sponsorship dollars.
Contrast that with average joe skiing- if he has a modern ski boat with a good wake- well that's about it. maybe he'll buy a new ski every year or try to win one from ball of spray, but the average joe skier isn't trying to impress his friends to create the "party barge" so he can feel cooler. I can't speak for every skier out there but I think most average skiers ski for themselves, not to impress others. And if @horton comes out and skis -39 behind my boat I might feel slightly cooler, or less cool, I'm not sure which.