When looking at this from a psychological viewpoint: "people" have a tendency to try to belong to a group. It makes them feel secure. It doesn't really matter what the group is about: sports, cars, beer, camera brand, you name it. So if you have made your choice it's important to stick to this. You will try to ignore information that's not congruent with your conviction. But secretly you are interested in what's going on with the "other" product, especially when this product gets positive reviews. Actually, you ARE interested. This generates fear, anger and negative remarks on forums. (Yes, a little over the top; but there is some truth in this....)
