Well, you can't set odds for someone who literally always wins; the only way you could make money is by luring people into betting against the dead cert. And I'm guessing underground robo fighting is a small enough world that you wouldn't be able to do that for very long. People would get wise. It would also get more and more difficult to find people willing to fight against this monster.

Also yeah, Marcia said "robot"! I thought that was a four letter word around here...