What makes bully breeds particularly dangerous if they are raised to be aggressive, is that they can actually hurt people and other animals due to their size and physical structure. But what's wrong with that sort of thinking? Well: I'm a tiny korean jew. Put me next to an NBA player and ask the question about who is more likely to fuck you up in a fight. Does that really mean anything? Is this a fundamentally loaded question which presumes something different about pitbulls than all other dogs? There's a lot of qualifiers in your sentence for a reason, and my answer would be kind of the same as it would for any race--it depends on how you slice the factual data. Do I think a black person or pitbull in a poor neighborhood, in an area with a large wealth disparity and low education would be more likely to be dangerous than the overall population? Statistically they are. People are apex predators with a prey drive, too, don't assume dogs are all instinct and you're a tabula rasa. Do I think that if you took away all the confounding factors you'd be able to see increased aggression from the breed? Maybe, but I doubt it would be more than many other breeds.
That's specifically what I'm saying about pitbulls. The concept that they all have an aggressive prey drive that is unique or more severe than any other breed simply isn't true. They do tend to have more of it than others, but you can breed that out as much as you can breed it in, and you can express those tendencies on a wide spectrum.
What you are trying to ask in comparison is, "is a bully-breed dog more likely to bite or injure people than other dogs if they were to be brought up aggressively?" Unfortunately a direct answer is difficult to achieve. You can use epidemiological data to make inferences and do multivariate analysis, but to answer your specific question, you'd need large numbers of multiple dog breeds in a control group where they are treated well, and large numbers of multiple dog breeds where they are abused. Those dogs would have to be destroyed, and you're not going to see many people funding that kind of research.
Even with their aggressiveness, a chihuahua isn't going to kill anyone. But a chow could, a lab could, a berner could, a mastiff could, etc. There are PLENTY of large breeds capable of hurting people and that have been bred for a wide variety of guarding behaviors, but they are also minority breeds, where as pitbulls are incredibly common. It isn't a simple thing to discuss, so sweeping generalizations or putting dogs in simple boxes like "dangerous" just don't make real sense if you want to engage these issues properly.