Trying to win the day can mess up a lot of your tomorrows. When you try to win the day, you might get caught up in things like getting the last word, or the best word. It can feel like that was the thing to do at the time, but you can wind up hurting people's feelings and having them come at you much harder the next time, if it goes that far.
Winning the day can seem childish, but many people involve themselves with it. It can involve a war of words, or it can involve a lot of disrespect.
A lot of people who win the day, walk away with the feeling that they have told someone something that they needed to hear, or that they "Got it off their chest".