Why are people fanboys?

I am sure there are many good reasons such as they have the best hardware available or they have excellent customer support. But that doesn't mean that they should say that everything else is below them and they are right.

1 person may be an Intel fanboy because they don't like AMD, but another can be an AMD fanboy because they don't like Intel.

But neither have a good reason to be a fanboy.

Why not just buy the...