http://en.wikipedia.org/wiki/Luxury_good
Branding: Valverde rides Pinarello; Cunego Willier; Boonen specialized; Sastre Cervelo.
Accessibility/Identification: People can actually buy the technology they see in action on TV. In case of soccer or NFL people buy shirts and other merchandise, but apart from the actual game ball there is nothing more. On the oter hand, when people see F1 racing, they can only buy merchandise, because it's hard to come by an actual F1 Ferrari.
Marketing 'brand+higher price is better quality': however due to the possibility to lowering labour costs by shifting to low cost countries, as well as increased efficiency and productivity, companies are able to yield huge profit margins. Don't Armani or Hugo Boss already produce suits in China? If they do, a suit costs probably less than 10$ but it sells for >1000$.. kaaaaaaching! (or cashing). If Specialized produces its carbon frames in Taiwan at a cost of 1/5 ot the retail price, lumped together with Boonen and a succesful classic season, people WANT the bike at all costs... Lower cost and higher prices also mean that more money can be spent on 'marketing and branding', mainly by signing high profile athletes. Isn't it funny that Tiger woods makes a lot of money just by having his picture taken with a fancy watch, or Beckham in CK underwear? People who consequently buy these items (worn or not) basically subsidize these athletes in purchasing a 5th home in LA or a 3rd jaguar...
Marketing and tech: Cycling is a pretty tech driven sport, so almost every product is 'scientifically developed'. A$$os does a$$ research and every nipple and spoke on a lightweight wheel set is nerdified by a team of nipple and spoke experts to 'prove' that they are the lightest, strongest and most durable nipples and spokes ever invented. Researchers are usually on the higher end of the pay roll.
On top of that, patents prevent competitors to use the advancements, so they do the same work again, and come up with a slightly different solutions to the same problem. Patents need to be protected, so a whole legal team is employed to sue each and every one who comes even close to sniffing the nipple and spoke. Lawyers also tend to be relatively expensive (but the money saved by employing Birmese children to put the nipple and spoke combo together fortunately off sets some of these costs... ie socialism for the affluent $)
That scientifically developed chamois that prevents your reversed cleavage from turning to ground beef after a 4 hour ride, is something they value at $300 (including lawyers charges) and which you are willing to pay...
congrats, you just hired yourself a legal team, employed birmese children and a geek!
On top of all this, some teams sometimes even use different material (not known to the general public) and spray paint the logo of their main sponsor over it. So while some believe a Giant is the best bike out there, it might actually be something else =)