This is a good question. Let me give you the context of these words. These words come around lines 640-650 in Sophocles's Oedipus Rex. These are the words that Oedipus speaks to Creon, whom Oedipus accuses of trying to usurp power from him. Oedipus thinks that Creon and Tiresias are trying to trap him and take his kingship away.
Within this context, these words are Oedipus's attempt at saying that Creon is foolish if he thinks he can take the city of Thebes without numbers of solider and money. Oedipus is basically saying that kings are made by money and power. Here is the fuller quote:
"Has your face grown so bold you now come
to my own home—you who are obviously
the murderer of the man whose house it was,
a thief who clearly wants to steal my throne?
Come, in the name of all the gods, tell me this—
did you plan to do it because you thought
I was a coward or a fool? Or did you think
I would not learn about your actions
as they crept up on me with such deceit—
or that, if I knew, I could not deflect them?
This attempt of yours, is it not madness—
to chase after the king’s place without friends,
without a horde of men, to seek a goal
which only gold or factions could attain?"
From these words, it is clear that Oedipus is truly blind. No one was trying to take power from him, especially Tiresias. Moreover, we an see his blindness in that the "kingdom" (Thebes) was taken from him without money or men, but by his own hubris and actions in the past.