Betting against "your team"

[protocol]

Tonight I did something stupid. I bet against the team that I have been rooting for my entire life. This was my first ever sports bet, but I felt strongly that the line was off.

Of course, my team lost AND covered(to make it worse). Watching the game was a sickening experience. I've heard that you shouldn't bet if you are emotionally involved with one of the teams, and now I know why.

Does anyone regularly bet on or against their team?