I don't think I apologize that much. But, like FL, I will frequently abandon an argument very quickly in the face of opposition, unless I really care about the subject and have already thought it through carefully. However, I only really do this with arguments which become personal. If the argument is more abstract I have no problem with arguing for the sake of arguing. The reasons I tend to quickly abandon arguments fall into 2 categories:
1) I realize I'm wrong (quite infrequent, to my shame).
2) I realize I could be wrong and need to give it more thought.
3) I still think I'm right but need time to put my finger on the fault in the other person's argument.
4) I know I'm right but can't be bothered trying to prove it. Prefer to leave the other person to their ignorance (pretty frequent, to my shame).