to know yourself is to destroy yourself?

Are you referring to Oedipus's tragic flaw? Oedipus has a clear hamartia - or tragic flaw - which precipitates his woeful fate. in this case, it's his pride, which allows him to disbelieve the Gods and hunt the source of a plague instead of looking inside himself.

no i want the answer what kind of ruler was he his attitudes towards the people of thebes..