The Pharaoh made all the efforts that he could to control his people. The belief in Allah, or "Iman' as it is called by the Qur'an, is a great power. When it finds it's way into one's heart, one finds himself as powerful as to face the whole world and all the forces gathered together against him. This was a great change. Only a few hours ago, the sorcerers were the worshippers of Pharaoh, but having faith in Allah they demonstrated such a great power and courage that in response to all the threats to their lives by the Pharaoh, they only said with perfect satisfaction that, in that case, إِنَّا إِلَىٰ رَبِّنَا مُنقَلِبُونَ "To our Lord we are sure to return."
The sorcerers were fully aware of Pharaoh's power and authority over them. They did not say that Pharaoh will not be able to kill them because of their new faith. Their answer was to suggest that the whole life of this temporary world had no value in their eyes. Their satisfaction was due to the fact that they were sure of meeting the Lord of the worlds after passing away from this world. There they shall get an everlasting life of peace and comfort. Another interpretation of their answer is that though the Pharaoh had all the power to finish their life, but soon he will be presented before the Lord of the worlds where he shall be taken to account for his despotism. In another verse, the following statement is also included in the answer of the sorcerers, فَاقْضِ مَا أَنتَ قَاضٍ ۖ إِنَّمَا تَقْضِي هَـٰذِهِ الْحَيَاةَ الدُّنْيَا You may pass any judgment you can against us, but your judgment will be restricted to this worldly life." (72:20) This also shows their total indifference towards the temporary life of this world.