Hardware sales are declining, but prices are not. The only reason I'd want to build a pc would be for gaming. Then I look at the graphics cards prices (edit: and CPUs!) and think twice! It's become so expensive to be a pc gamer, that consoles make more sense nowadays. My personal desktop pc has become a dev tool. Really, the only reason I would want to purchase a brand new system would be for games.
I honestly can't see why non-IT folks would want to fork out thousands just for a new computer. Their 4-5 year old laptops or desktops are more than adequate for spreadsheets, websurfing (which most people I know prefer doing on tablets), facebook and the occasional Spider Solitaire.