You don't always have to have the last word.
This is something that took me many years to learn. It's not something that I learned from the publishing industry, and thank goodness for that, or I shudder to think what my reputation would be like.
We all know people who have to have the last word. Some are only like that when they argue, and some are like that about everything, not content unless theirs is the last voice in every discussion.
Don't be one of these people. Start practicing now.
This will become important in your publishing career, because as an author you very often don't get to have the last word. You put your words out there, on paper or digital document, and then you give them to an editor. The editor will make changes, more than likely, and sometimes you won't agree with the changes. Yes, you get to express your opinion, but ultimately, the editor or the publisher will probably have the final say. This is a case where you don't get the last word. (See my post on working with your editor for more details.)
Then, once your work is published, you're done with it. That's pretty much the end of the discussion for you. Unfortunately, it's just the beginning of everyone else's discussion. Eventually someone is going to give you a bad review. It may be an anonymous commenter, or some guy with a blog, or the New York Times. It doesn't matter. Your part in the discussion is done. This is one instance where you really must not attempt to have the last word. (Read Nathan Bransford's excellent post on this subject here.)
I learned this valuable lesson when I worked at a company full of passive-aggressive people who always had to have the last snarky email in the email thread, no matter how right or wrong they were. Eventually I learned it just wasn't worth the argument. Sometimes they'd make me so angry I would type out a huge long snarky email reply…and then I would delete it. I felt better and the discussion, which was usually completely irrelevant and unproductive at this point, was over. (Note: if you plan to do this, do NOT put anyone's email address in the "To" field. "Delete" is so very close to "Send"…)