Not everyone can afford a Harley, but most people can afford the merchandise. Everytime I see somebody wearing a Harley shirt while not riding I wonder if they actually have a Harley (although this town is downright maggoty with FNGs these days). I've been known to ask a few what model they ride. I've also been known to ask people wearing Sturgis shirts about their Sturgis experience. Nine times out of ten their friend/brother/cousin/etc. got the shirt for them.
Also, at the risk of sounding sexist, the clothing draws the women in. If they can hook the wives, whether they have their own bike or ride pillion, that drags the husbands in, too, who tend to spend money everytime they come in. It's all very insidious and marketing brilliance.
