There was nothing else to the fight, so he couldn't spot a weakness, and he didn't see anything that he could have done better to avoid the fate of being captured and subjected to existence-rending pain. His defeat was as straightforward as it could be and there was no denying it.
At the end of the day, he could only say, "I shouldn't have come. I shouldn't have been greedy."
This was his final conclusion. It is all he can figure out from the humiliating defeat. Unfortunately, it is too late to come to that conclusion now.
After all, it is of no use to have such an epiphany now that he has been captured. It certainly won't help him break free.
In fact, if someone had told him to avoid the dragon at all costs before he encountered the dragon, he would have scoffed at them. He might have even scorned them for cowardice and foolishness. This was because every piece of information they had about the dragon indicated that it was weak.
