"You must have thought I was bluffing"/"You lost because of your ego" NO and NO!
Bond had a very strong hand, ace-king on a board of JKAJK, "rainbow" (no possibility of a royal flush). His opponent had the stone nuts (the actually unbeatable hand: two jacks in the hole for "quads", four of a kind). That's just bad luck for Bond. You can't "play scared" in Hold'em, meaning playing so conservatively that you fold a very strong hand just because someone might have the nuts. (Omaha, okay, different story.) It's not ego, it's playing the percentages and preventing super aggressive players from running you over.
"You must have thought I was bluffing, Mr. Bond." What a stupid thing for Le Chiffre to say. Bond did not have a "bluff-catcher" hand. That's a medium-strength hand that can pick someone off if they are betting big with basically nothing (or "air", is it is called in poker). From Bond's perspective, Le Chiffre might have the remaining king, ace-jack, or just one jack, any of which would give him a weaker full house than Bond's. A pair of aces or jacks in the hole were the only hands that could beat Bond.
It's fair to say Bond should know Le Chiffre is less likely to have a solitary jack, because then he's turning a fairly strong hand into a bluff (a poker no-no) since there's nothing Bond can call him with that he has beat. But Le Chiffre might have a king or ace-jack, hoping Bond has a weaker full house and "has to see it". He also might not expect to be called but planned to show the jacks if Bond folded, to discourage him from calling later when he really was bluffing.
It's certainly possible for a strong player in Bond's position to fold that hand. But you would need a really good read, or a sense that you can get him later and that it's not worth the risk. To call there does not indicate that he is sure the other guy is bluffing, or that he let his ego get the best of him.
If this is the way they needed the story to play out, they should have given Bond just a king (no ace) or even something like a pocket pair of queens, which really would just be a bluffcatcher hand.
EDIT: What I neglected to notice initially is that Le Chiffre didn't even know he had the nuts! For all he knew, Bond could have had pocket kings, giving him a higher four of a kind (in many casinos you will win a bad beat jackpot if you lose that way, but presumably not at the ritzy place they were playing).