Can't really blame people for the way it turned out. At an event like that with prizes you just have to expect people playing to win first and foremost.
I'm a big believer that EDH is all about having fun, and the one thing that keeps any game of EDH fun is having all the participants know the what kind of power levels everyone decks are. It's why I ask people that I haven't played with what kind of competitiveness they want to go with.
If everyone is the same power level, it's going to be a good game. If one person is strong, and everyone else is weak, that strong deck is going to be facing a challenge since they will be a target.
Communication is key. I've found that winning or losing doesn't matter as long as everyone gets to play their deck for at least 6 turns they will be happy.