no all dogs can be if the owner makes them like that, its just pits were bread for fighting, and alot of people used them for that!
ridgebacks in south africa are used to protect farms and houses and were originally bread to fight lions lol, but people dont think they are dangerous, rottys and dobermans also have historys of attacking people but 99% of the storys are down to the owners making them like that...
its a pretty shallow minded oppinion to have tbh ... treat a dog good and it will be a good dog... treat it bad and well there ya go...
It's down to temprament. Usually the nature of these well built dogs is that much more aggressive than that of say the Spaniel, Lurcher, or dalmation breed.
Yes alot of how the dog will react to humans in various situations is how the dog is raised. But it's much more likely that these aggressive dogs will inflict much more damage to a person than a dog without the muscular ability to do so.
I used to believe that it completely down to how the dog was brought up. A friend had Staffordshire Bull Terier. Wonderful dog, assertive but not vicious. Until one day it turned on him and tried to maul him. Luckily he escaped and isolated the dog in his house. Eventually it calmed, but no amount of dog training helped. Eventually it had to be destroyed. Raised from a puppy in family environment, well cared and well looked after.