I think people defend the things they are invested in. For example if you have bought Macs and invested time in learning to use OS X, you are invested in Macs a

I think people defend the things they are invested in. For example if you have bought Macs and invested time in learning to use OS X, you are invested in Macs and will defend them against competition. It is not just about personal preferences, but about the value of your investment. If nobody uses Macs anymore, your investment in Apple knowledge loses a lot of value. Likewise, if you have invested in building a Facebook network, you have an interest in Facebook remaining useful to you. It's more than just personal likes and dislikes, it's long term investing.