Some people always have to win. They cannot accept defeat. They feel they must win every argument and always be right!
What if someone disagrees with them? "Something must be wrong with anyone who disagrees with me, since I am always right!" he figures... and off they go spreading Loshon Hora. Nothing is too terrible to say, as long as in the end they get their way.
Look at these two men. Each wants to load his package on the poor suffering donkey and what a fight they are having about it! Neither man cares about anything except getting his way.