Human beings have this weird tendency to root for the weaker. We don't want to see someone who is already successful being successful again, we want to believe that anyone can be, so it give us hope that we will be successful ourselves one day. But in the moment that the weak become the strong, we forget their humble beginnings and that we supported them because now they remember us that they succeeded and we don't. That is why it is so easy to find people who now state their hate for something they loved in the past.
The really interesting part is that sometimes the only difference between this relation is the success itself, not that the subject of our rooting changed. Take Call of Duty as an example. People loved Modern Warfare, and now many hate it. The games changed almost nothing (one of the complaints, in fact, about the series) and now many can't withstand it anymore. And what changed was not the company behind it or the games, just the amount of success in it.
We want to see new things succeeding. Not because of any logic, but because we want to hope we can succeed someday.