Because your average person isn't an enthusiast who builds their computer themselves, who knows better, and will necessarily change their buying decisions and h

Because your average person isn't an enthusiast who builds their computer themselves, who knows better, and will necessarily change their buying decisions and habits. Instead most buyers choose whatever is good enough and convenient, or whatever brand they've typically historically trusted, or whatever their peers end up getting, or whatever an advertisement/reviewer/salesmen tells them because they're ignorant and not tech savvy. Then you have reasons associated with vendor lock in. I mean, most people buy DEVICES, not CPUs, and device manufactures are hesitant to switch, because doing so can potentially be complicated and prohibitively costly (especially if they already have deals with their current vendors). Whereas their customers will end up buying their devices regardless of whether they switch CPU vendors or not (because of reasons mentioned above)... Ergo, as other's have already sort of alluded, it's largely because of branding, marketing, and vendor lock in.