Why do people boo? It's like people who heckle comedians. They are the ones who paid the money, so why pay to boo? If you dont like the fight, why not, you know, just sit there not enjoying it, Dudes acting like it's a fuking pantemime.
If I was at an event, and the dude next to me was booing, I'd check to see if he was big or not, if the latter, I'd tell him to fuk off.