Consumers care if one business does better than the other because of two reasons, pride and long-term self-interest.
1) Everyone prefers to be on the winning or "proven-right" side. It's hard to be happy with your otherwise decent Blackberry if your peers increasingly don't use it, know anything about it, or disparage it.
2) There is also a long-term self-interested component that seeks more than simply trying to fit in. It goes like this - the more cool your chosen device/platform/game is the more users it attracts, the more users it attracts the more money is flowing through the system, and ultimately more money means more human resources are spent on patching/re-releasing your favorite product so that it can be improved and stay reliable in the long-term. And if it's a proprietary messaging system or a multiplayer game, having more users in the system is in itself also a boon to the end-user experience.