Why did the Israelites worship the golden calf after seeing God's miracles?
Their worship of the golden calf was an emotional choice that satisfied the flesh, not a response to any lack of divine proof. Despite God's fire, cloud, and deliverance from Egypt, they willingly corrupted themselves, rose to eat, drink, and play before a lifeless idol.
Les explains that although the Israelites had seen the proof of the Almighty God in fire on the mountain, the pillar of fire at night, and the pillar of cloud by day as they came out of Egypt, they still went down into idolatry and worshiped a stupid golden calf, a dead thing with no life. It was an emotional thing that appealed to their emotions. With the calf in the center of the camp, they sat down to eat and rose up to play; it was a practice of the satisfaction of the flesh. God told Moses to get down because the people had corrupted themselves. Les emphasizes they did it of their own volition, they asked for it. They were not victims of circumstance but people of choice who made choices.
Neither be ye idolaters, as were some of them; as it is written, The people sat down to eat and drink, and rose up to play.