The breed is schizophrenic. They can be the perfect pets but something will trigger them to suddenly snap. Only a fool will trust one. Yes, 95% of them will never snap but is yours in the other 5%? Are you positive it's not? Many others have made that mistake and paid with the lives of children.
That is a trait shared by many dog breeds and even wolves in the wild. The "killing frenzy" is common among many breeds.
Almost any young bird dog inside a chicken coop.
A terrier in a barn full of rats.
A wolf (or black bear, for that matter) in a flock of sheep.
A wolf among a pack of hounds.
Coyotes among a herd of deer attempting to cross a slick frozen reservoir.
Our JRT was the sweetest animal on earth, and lived for when the grandkids came to play.
But put a furry rodent, or raccoon in front of him and the "kill switch" flipped, He became deaf and blind to anything but the need to kill what was in front of him. He got into the yard with a dozen turkey poults and killed several with my wife beside him screaming and beating him in the head with her fists. The dog was totally unaware of her presence.
If he had been 60 or 70 pounds, I would have killed him before he was a year old.
Hell, back in the '80s, we had a little 2 1/2 lb teacup yorkie which attacked a fully grown ewe sheep. She did enough inoperable damage that the sheep died a few days later.
There is one difference between a pitbull (or wolf) and many other terrier breeds. Most of the terriers, we can drop kick over the fence if need be. Not many people can successfully drop kick a vicious pitbull into the neighbor's yard.