Also, in some cultures living as a slave could actually be more comfortable than living as a free man depending on the master. And many cultures made ways for slaves to free themselves, sometimes with honors and wealth. For example, being a slave in Rome could mean fighting in the coliseum, but if you did well, you could be made free and have earned quite a fortune in doing so.
And there are plenty of examples in America where slaves bought their freedom, and even ended up owning land, and even slaves themselves. I think about 3000 total throughout the period America had slaves were slave-owners who were once slaves themselves, though I could have that number wrong.
Even if that number was right, it's a drop in the water for all the slaves that never got any sort of chance like this. And they certainly weren't living comfortably.
The point about Rome is especially bad to me, given that fighting for your life in the Colosseum for freedom is hardly merciful.
Not to say that I don't agree with what you all are saying. Slavery is certainly.... how should we say... influenced, by gradeschool inadequacies and Hollywood mandates.
But lets not fool ourselves here, the reality is that these little loopholes and lights at the end of the tunnel were kept there to make others think they too could succeed within the system of slavery. Just like how the Colosseum itself served to distract the public from all their problems.