How is slave labor preferred over indentured servants

Indentured slaves are like people in debt. You would usually lose the worker after 7 or so years when they worked off their debts. You would be able to keep a slave for a lifetime or even sell them for money, you can't do that with an indentured servant.

Indentured servants were people who did work for a planned amount of time unpaid for passage into the united states. Slaves were people who were owned, and usually worked against their will. Indentured servants eventually got to stop working while most slaves didn't. Slaves were often treated much worse than indentured servants.