The difference is that people have free will and choose to engage in fights. Dogs that are trained to do so have no choice - they are beaten, starved, deprived of water, anything to make them fight. They fight or they suffer and die. That's so basic that I would have thought that it would be obvious.
And pitt bulls are no different from other breeds - they are no more vicious than other breeds unless trained to be.
And as for underperforming, if we apply the same logic to Vick, he would be facing a death sentence based on his performance in the NFL.
Perfectly said AR! Amen brotha, I sooo concur!