Explain how southerners used states’ rights to justify owning slaves please

Wasn't one of the reasons was because of cotton farming being their main business. They felt like if there were no slaves their won't be any business for them. One other reason was that they thought slaves were their right and specifically property. And they believed government can't take away property

to extend a country’s power and influence

sitting in that one chair where he could get shot at was his worst decision.