Saul erected a monument to remember and celebrate the victory over the Amalekites. The fact that he did so in his own honour suggests that he considered himself to be the chief author of the victory. Saul saw the battle as his and not the Lord’s.1 Since he thought the victory was due to him, he believed that he had a right to share in the plunder and participate in a celebration where the defeated enemy's king was put on display.2
12 And Samuel rose early to meet Saul in the morning. And it was told Samuel, “Saul came to Carmel, and behold, he set up a monument for himself and turned and passed on and went down to Gilgal.”