Healthcare professionals need insurance for these primary reasons:
Meet legal obligations - Each state determines legal requirements for healthcare professionals licensed in the state.
Pay for lawsuits - Doctors get sued by patients all the time, but having the right insurance pays legal costs, including settlements.
Good image with patients - Having insurance in place makes patients feel comfortable that their doctor adheres to professional standards.
Since any doctor can get sued by an unhappy patient, it's important to have insurance to pay legal costs instead of paying out of pocket.