This isn't really surprising. Do you know how much is spent in Western countries every year (much of it wasted) by people trying various stuff to keep fit?
I notice that the giving up rate for Wii Fit is as high as gyms, etc. which confirms that many purchases were made 'in good' faith as a way of keeping fit... then went the way of the next bacon sandwich.
Try to be reasonable... its easier than you think...