I think that the demographic thing (education and income level) has more to do with being able to afford the equipment necessary for a comfortable tour. I'm sure that you can do a cycling tour without a bike that is over 1000$ and without fancy shorts, but I don't think it would be nearly as comfortable.

I think that cycling is geared more to upper-middle class - most people I know wouldn't dream of spending over a thousand dollars on a bike. Then again, a lot of people are willing to spend that much on a high end television, and to me it evens out - I use my bike more than I watch tv.