On youtube, why do Oakland Raider videos attract trolls from other teams?

I'm a Raider fan & I don't get why people would even bother watching a video from a team they dislike. Also, the Raiders haven't did s*** in years so I don't see why people still hate on them. What's also funny is that once I see fans from other teams in person, they're friendly & easy-going, but the internet tells a different tale! They don't have anything to say when face-to-face with Raider fans.