I believe it was Epic at GDC (2005/2006 can't remember) who asked the audience of mostly game developers "How many of you owned a Gamecube?" in an attempt to demonstrate that Nintendo was out of touch with most gamers; to his surprise most of the audience (about 75%) raised their hands.
A large portion of "core-gamers" love Nintendo for their high quality and purity when it comes to gaming ...
Nintendo "lost" the casual market with the N64 and then lost a lot of more core gamers with the Gamecube; as a guess the casual gamers went to the Playstation and the core gamers (in North America) went to the XBox.