Extra Anger Inducing effect of, during Deibu's delusion, seeing a shithead deibu beating up a little and cute girl because she didn't want to give her candy and was getting tired of the deibu's harrasement?
Anyway, aside of all the obvious yukkuri reasons that doom such actions, the reason Deibu failed in her "attempt" at boxing was because she was a gutter trash that lacked dignity!