Why did south carolina want to overthrow the proprietary government between 1719 and 1729

There were several events that triggered the stated outcome, but a few of the most significant are listed next:

The Lords Proprietors of Carolina "administrated" their colony for personal economic benefits, which resulted in an uncontrolled management of it. The failure of the proprietors to assist South Carolina during and after the devastating Yamassee War (1715–1718) and against pirates (1718–1719) led colonist to conclude that men in London had no interest in public welfare. A last even is associated to the failure of guard against Spanish encroachments from Florida.

Ummm they were radical