Matt feels guilty because he can't save everyone - cases against corporations that he and Foggy can't win, and the constant background noise of people in the city getting hurt.

He remembers every cry, every scream, every victim. When he goes out as Daredevil, he doesn't defend himself very much, even if he does win. He lets the scars and bruises collect on his skin.

Cue Foggy noticing how bad Matt looks one night and telling him: "Dude. You have to stop."