Slavery was introduced when white people discovered Africans and wanted to use them to do labor on their farms. It increased wealth, because with more people at work, things got done faster, thus they got more money quicker.
or those not heavily vested in the economics of slavery, the 'peculiar institution' offered the best means the white South had for controlling the Black population.
Slavery had become entrenched in the South due to their agricultural economy. The way things were set up, slavery was necessary for the way of life that had developed there.