The man you're insulting wrote this:
We all have our own individual views on war… But, doesn’t that speak to just another thing that makes this country so special?? The fact that we can all wake up every morning and BE individual with a pure sense of freedom..? But, one thing that can’t be argued is that it’s because of the people who VOLUNTEER their lives to make sure that it’s protected at all times. And, like I said before, doing so while asking for nothing in return…
To people like me who get to benefit from this type of person… One with character and courage. With strength and bravery. With humility and honor… I say: Send your thanks. Do it however you can. Write a letter, type an email… Hell, buy ‘em a beer next time you run into someone from our Armed Forces in a bar. When they say thank you for that drink that cost you 3 bucks, they’ll mean it. They won’t take it for granted and, they won’t forget it.
Your snide insult does honour neither to you, nor to the United States Marine Corps.
You owe him an apology.