In Exodus 9, God brings a plague against the livestock of Egypt. The Egyptians worshiped their livestock yet enslaved people and treated them horribly. God wants His people free from oppression so they can worship Him. God wants us free from sin and oppression in our lives so we can freely worship Him with all our hearts, minds, and souls. God sees that Pharaoh is not going to change his heart regardless of multiple chances and warnings. In the next plague, God steps in and confirms Pharaoh's heart is truly hard and his time is up. After the plague of hail, Pharaoh shows fear of the consequences God is bringing forth which is merely regret, not repentance. God knows the difference. God affirms His power and authority over the whole Earth and that the Earth belongs to God. This isn't just God versus Egypt's false idols, this is about the whole Earth and God bringing refuge and freedom from bondage for His people.
