You keep comparing the colosseum killings to events that transpired over large geographical areas, for different purposes than entertainment. As me and others here have pointed out repeatedly, what makes it special (to us, not to you apparently) is the fact that all those killings happened on a single location.
You cannot measure how primitive a culture is by the amount of people they kill.
To me (and, I would argue, most people), the monument symbolizes specifically those often pointless killings and nothing else. That is what it is famous for.
Unfortunately, your replies regularly border on the insulting. You keep pointing out how the arguments you present are things I "fail to understand" or prove my lack of knowledge of historical events, often telling me to "go read a book", like I'm some rambling child. Meanwhile, you have not told me anything I did not already know.
I'm done with this discussion, as it does not appear to go anywhere. Good luck with your opinions, I'll hold to mine.