Because apparently, a few bad apples ruined the reputation of the whole bunch. I for one, know that it is the owners who I should blame for those Pit Bulls being like that. People think just because one of them did harm, that they'll all do harm and don't even give them a chance to show how kind they can be. >:(
I had a friend with a "well socialized" pitbull that attacked both of my dogs at least once and bit my old blind cat too. Another friend had a pitbull that attacked and killed their little dog that it had been raised with. I don't think I could ever trust any of this breed if these responsible owners couldn't manage to have safe dogs.
Pit Bulls have a natural temper, which can be controlled if they're raised correctly. However, due to their ability to build muscle and their strong will power, they are often times used for dog fighting. Because so many get loose and harm humans, many people fear them because they do not understand. They were used in ancient times as fighting dogs as well, because they are built for hunting. However, if you ever get to know a Pit Bull, you'll learn that despite their size and strength, they're just teddy bears. They have good hearts, and they protect the ones they love fiercely. (If you're against guns, just git a Pit Bull!)
they were originally bred to be vicious. i'm a dog kinda guy but if they euthanized every pitbull in existence it would not bother me. In less than one week a pit in Albuquerque attacked and killed his owner and one in so. new mexico attacked and killed a neighbors 18 month old baby. they serve no useful purpose.