In Cormac McCarthy's novel No Country for Old Men, Lewelyn Moss proves time and time again that he is overconfident in his ability as a hunter, a Vietnam veteran, as a fugitive, and as a protector of the money, his wife, and his own safety.  Indeed, Moss is in over his head as a criminal, as Carson Wells points out:

You're not cut out for this.  You're just a guy who happened to find those vehicles.

First of all, Moss tries to make an impossible shot on a distant herd of antelope.  Not only does he miss, but he wounds the animal.  Then, after he finds the money, Moss goes back to the scene of the shootout to give the dying man water--an act of impossible benevolence.  Then, Moss sets out on life-or-death chase against a psychopathic killer, his criminal organization, and the law--all the while leaving his wife and mother exposed for reprisals.

Even sherriff Bell and deputy Wendell know that whoever is chasing Moss is kin to the devil himself:

This this boy Moss has got any notion of the sorts of the sons-a-bitches that are hunting him?

He's seen the same things I've seen, and it's certainly made an impression on me.

But it doesn't make an impression on Moss.  He seems certain that he can make a clean getaway.  His overconfidence is a by-product of greed; it blinds him.  When Carla Jean tries to warn Moss of her bad feelings regarding their split, Moss answers with coy arrogance:

I got a bad feeling, Lewelyn.

I got a good one.  Oughta even out.

In the hospital, even Wells tries to warn Moss of his inevitible fate.  But every time Wells tries to give Moss information about his stalker, Moss snaps back with overconfident denials:

You know how he found you?

Yeah, I how how he found me.

It's called a transponder.

I know what it's called. He won't find me again.

But, it takes two shootouts with Chigurh for Moss to realize that his satchel is being tracked.  Moss finishes the exchange with Wells using classic overstatement:

Maybe he's the one that needs to be worried about me.

Even Carla Jean tells Bell that Moss can "take all comers."  She is blind too.  And even after Chigurh talks to Moss and tells him where he's going (to kill his wife and mother), Moss again thinks he can outwit Chirgurh, death, and fate.

So, time and time again Moss thinks that his coin will always land "heads."  He is in complete denial of the two-sidedness of the coin, death, and the evil that chases him.