Apt Metaphors

Pit bulls were bred specifically for the purpose of "entertaining" people by being tossed in a pit where they viciously attacked a bull (or, sometimes, a bear) that was sometimes tied to a stake. The "entertainment" lasted until the bull (or, sometimes, bear) was immobilized. Then it was either time to get a new bull (or, sometimes, a bear) or to grab a pint and head home to thrash the wife and kids before passing out. The bull oftentimes had pepper blown into its snout to make the contest a little more interesting. Usually the pit bulls were set upon their prey in a pack, but sometimes they were put in the pit one at a time to see which one could "pin the bull" by latching onto its snout and not let go. (Other kinds of baiting involved pitting dogs against badgers, hogs, donkeys, ducks, rats and the occasional exotic animal such as a lion. There was also human baiting, which involved a man, sometimes tied to a stake, trying to punch a dog.)
When bull baiting and bear baiting were made illegal the pit bull was used for dogfighting.
They still are.
Humans created pit bulls for vicious entertainment. We made them so we could watch them rip apart large animals and "be amused." (Ah, the many-splendored gifts of humanity and civilization...)
So, pit bulls were bred and trained for blood sports to entertain people who wanted to watch some killing, but didn't have the grapes to jump into a pit and fight a bull or bear themselves.
Consider these facts, then, if you're thinking about using "pit bull" as a self-description. It may not have the connotation that you want it to have.