As a result of Yaakov's having taken the blessings, Eisav hated him with an unquenchable hatred that sought revenge. He devised a plan whereby he could dominate the world.
Kayin killed his brother Hevel before his father Adam died. That was his mistake. After Hevel was removed, Adam had another son Shais. Therefore I will do better, I will make sure that both my father and my brother are dead.
Eisav waited until Yitzchak died before attempting to kill his brother. Did he not realize that his brother would meanwhile have children? I will be smarter, I will drown all newborn boys in the river.
Pharoah didn't realize that the girls would marry and bear children. He should have wiped out the girls as well as the boys. I will be the one to wipe out all of them.
At the end of days, Gog and Mogog will say:
Didn't Haman know that they have a Protector in Heaven? We will first overcome their Protector and then destroy them.
But Hashem answers them all: "I have many messengers to frustrate your plans". Then Hashem will go out to wage war against the nations, and on that day Hashem will be the sole King of the Earth.
Source: The Midrash Says