Oedipus, Creon, and Antigone did help their own downfalls along. The gods did deal each one terrible situations, but pride caused the total destruction of each.
Oedipus, trying to avoid the wrath of the gods, leaves his own country so that the prophesy of his killing his own father would not come true. Right away, we learn that humans, by their own wills, cannot change destiny dictated by the gods. After unknowingly killing his own father, Oedipus becomes king of his new country. He also takes his real mother as his wife.