This is interesting actually. You see this happen often with people who identify with one political party or another. You get something of a herd effect where individuals tend to just follow their own ingroup, and everyone from the outgroup seems to be “wrong.”

Another example is with viewers of team sports. I might support my own university’s sports team without thinking about whether the team is actually good, but I would hate anyone from the opposing team’s side. There is no rational thought going into this. It’s really all a matter of belonging — being one with the ingroup.