Why does Percy feel ashamed that Poseiden saved him? Chapter 14

Percy was ashamed because he had to be saved. He felt that if he could save others.... that if he wasn't a hero, he wasn't good for much of anything.

Why had Poseidon saved me? The more I thought about it, the more ashamed I felt. So I'd gotten lucky a few times before. Against a thing like the Chimera, I had never stood a chance. Those poor people in the Arch were probably toast. I couldn't protect them. I was no hero. Maybe I should just stay down here with the catfish, join the bottom feeders.