Since about one-third of american colonists favored the British in the war for Independence, why was Benedict Arnold's attempted treason such a terrible act?

He turned against freedom. He turned toward a dictator of a king that didn't care. He slapped the Tea Act and forced treasons on people, poor people. It was only for his profit. Arnold, despite knowing this, became a turncoat and betrayed the patriots. Look at India. Look how badly they were treated. That's how British treated the public who opposed them