Why does Gilgamesh begin smashing the boat “with heroic violence”? How does this show his characterization?

Gilgamesh was angry with Siduri words.... that he must accept the decision of the ferryman, as to whether or not he will be able to cross the waters with him. Gilgamesh's anger and destruction speak to his impatience and belief that he is in charge... that his desires must be fulfilled.

When Gilgamesh heard this he was seized with anger. He took his axe in his hand, and his dagger from his belt. He crept forward and he fell on them like a javelin. Then he went into the forest and sat down. Urshanabi saw the dagger flash and heard the axe, and he beat his head, for Gilgamesh had shattered the tackle of the boat in his rage.