Oh, life is far too short for a Harley. Buy a Ducati or something. ;)
No seriously though the other reason 35-year-olds buy a motorcycle or convertible or similar pleasure vehicle is that they actually can afford it, unlike new grads just out of school? (I differentiate the pleasure vehicle from the utility vehicle; if you buy a little 125cc motorcycle as a car-alternative for zooming around town that's quite different than the speed machines, or the massive touring motorcycles that get SUV-grade gas mileage.)
Anyway, this is one of the positive parts of middle age — maybe you're not actually rich, but you're usually much better off then you were in your twenties, might have a good start on a home or a retirement, and can afford a few personal luxuries, or children.