That’s absurd to compare - slaves in antiquity were literally worthless, they had no capital value because they were war prisoners. Slaves in America were incredibly expensive capital goods - at the time of the civil war the aggregate American capital goods account consisted of >50% chattel slaves. They were so expensive there was a chattel financing market for it. To say that someone is going to arbitrarily have an American slave eaten alive by dogs or fight them to the death is asinine - it would be akin to lighting money on fire. That’s not to say it didn’t happen, it might have - but certainly not to the same scale that slaves of antiquity were literally worked to death or killed for entertainment.