Almost all dogs were bread to fight or hunt. There is some exceptions of course, but it’s the majority. If we were to kill every single one of them, we’d be left with chihuahua.

There is a HUGE difference between being bred to hunt vs bred to fight. It is disingenuous of you to conflate the two categories.

Most dogs bred to hunt are bred to not excessively damage the animal being hunted. A hunted animal is of no use to a human if the animal is ripped up and has its intestines contaminating all the meat, for example. These dogs have been especially bred to tone down their aggressiveness.

If we step up to slightly bigger game like, say, bears, dogs being used in that case are not bred to latch and hold on as it will likely get them killed. The dogs are to distract and chase. It is not a good trade to swap a single dog for a single bear. Again, those dogs are being bred to to not have a too strong an aggressiveness.

Hunting dogs are meant for the human to deliver the fatal blows while the dogs mostly chase, distract and retrieve. This means breeding to prevent aggression from becoming too strong.

Dogs bred to fight are precisely the opposite. The are bred to have high aggression and high persistence even in the face of existential threats to themselves.

There is no reason to continue breeding pit bulls (or any other fighting dog). Period. There are far superior breeds of dogs for any characteristic you can choose.