Why did Jesus allow the demons to destroy the swine?

And forthwith Jesus gave them leave. And the unclean spirits went out, and entered into the swine: and the herd ran violently down a steep place into the sea, (they were about two thousand;) and were choked in the sea.
Mark 5:13

“He [Jesus] allowed the evil spirits to destroy the herd of swine
--as a rebuke to those Jews who were raising these unclean beasts

for the sake of gain.
--Had not Christ restrained the demons, they would have plunged into the sea, not only the swine, but also their keepers and owners. The preservation of both the keepers and the owners was due alone to His power, mercifully exercised for their deliverance. Furthermore,
--this event was permitted to take place that the disciples might witness the cruel power of Satan upon both man and beast.
The Savior desired His followers to have a knowledge of the foe whom they were to meet, that they might not be deceived and overcome by his devices.
--It was also His will that the people of that region should behold His power to break the bondage of Satan and release his captives. And though Jesus Himself departed, the men so marvelously delivered, remained to declare the mercy of their Benefactor.”
The Great Controversy, p.515 E.G.W.