Can you believe what you have just said? That your expectations are such that a home team's fans will viciously attack opposing teams' fans? Unacceptable. (Not that I'd advocate doing that after this, just that in a civilized society one should expect decent behavior from both teams' fans at all sporting events.)
Being a "good sport" means winning, losing, and cheering with class and respect.
I don’t think we disagree about what SHOULD be. I’m saying that such sportsmanship obviously is lacking. If you’re saying my choice to avoid most games (when “my” team is the visiting team) is “unacceptable,” well, I’m not really interested in whether my choice would also be your choice.