What in the story suggests that Santiago fails because he is too prideful???
I can only think of one thing which might possibly indicate this. After Santiago has gone eighty-five days without catching a fish-- his record is eighty-seven--Manolin used to go with him, but he is now on another, mure successful boat. On the night before Santiago catches his great fish, Manolin does offer to disobey his father's wishes. "I could go with you again." They clearly love each other, and they would love to be able to fish together again. Santiago says no to the suggestion, and though the boy helps him get ready for another day of fishing, the old man is off on his own.
If Santiago had said yes, he would have had some help with his brother, the fish. Perhaps he says no because he is too proud to ask for help. I tend to think it's because he loves the boy, wants him to be on a lucky boat, and wants him to obey his father; however, it may have been pride.
In all other ways, Santiago is a man with little pride left--at least with the boy--which makes me disagree with the premise of your question.