Assumption: All of mankind is born free. They have free will and can make rationed decisions based on imperial knowledge that they can create or evalutate independant of any source. Borrowed from Locke.
It is interesting to ponder that so many have sold themselves and others into bondage. The gains seem so small in the big picture, but I think it is in the interest of the slave-trader for people to think about short-term gains. So the question remains, why are we so quick to sell ourselves into bondage.
Ok, maybe we go back a couple of thousand years to when life was even more brutal. Tribal life, there was a chief and you needed to listen to your chief if you wanted to have enough food for the winter. So in exchange for loyalty (not bondage, yet?) you gove up some of your freedom for collective security.