Oda bringing it full Circle. Wano started off with Zoro about to commit Suicide because of the Samurai way, but he found the real culprit. Kaido is jealous of Samurai because they are honorable (They die in great ways or if the shame themselves they commit suicide),but Kaido can't kill himself. Which makes sense why he respects Samurai so much.
Kaido wants to go out in a great battle, but he can't doe nor kill himself. This makes him depress. Lets say he considered what he did to Oden Shameful. A samurai would kill themselves, but he can't.