Meh, Richard was kinda in the right for most of the movie
1.) Their goofy personalities aside, Van WAS a loser while Richard was a respectable member of society. Come on, an aspiring doctor/student government president versus a "career" student thats mooching off daddy's money while picking no major? Only a movie aimed at teens would make the former a bad guy, and the latter a hero.
2.) Who cares if he cheated with that weird chick at the end? Tara Reid's character was emotionally (and nearly physically) cheating on him the entire film beforehand. It was completely justified for Richard at that point. Tara Reid's character was the worse person in the relationship.
Again, I am putting his goofy personality aside (the frat antics, the jerkishness, etc.). Obviously he was an ***hole, but conceptually he was in the right.