Why is serious bicycling associated with higher class people?

I think it has to do with cost and... leisure time!

The wealthier, more affluent members of society can indulge in their hobbies (yes, cycling is a hobby) more readily. In my part of the country, many of the people I ride/race with are either engineers, doctors, lawyers, sales/acct reps. They have high paying jobs and think nothing of not only spending RM3-4K on a bicycle, but have the ability to take time off from work and ride as little or as much as they want.

Working class individuals tend to have hobbies that are more cost effective (i.e. quads/motorcycles, boating) and indulge their hobbies as part of a family gathering on the weekend or a long vacation. As another poster mentioned, they also are able purchase their 'toys' with credit while a high-end bike is more of a cash-and-carry purchase.Mmmmm.....