Does Kaido just want to have an epic death like Oden? He killed the old hag and felt pretty bad about the way their fight turned out.
We got this ridiculous, over the top introduction that made Kaido seem like an absolute monster but after that we gradually got to see all his flaws one by one, to the point where his introduction is actually starting to seem like the one chapter that doesn’t fit his character.
Kaido made Oden dance like an idiot for five years because his army was weakened after the fight with Moria. Instead of challenging him again after he lost due to a trick he took part in the execution of Oden, which only served to make Oden look like an absolute boss.
I think the realization of the difference between him and Oden left a permanent mark on his pride. In the end he just shot Oden, maybe because he was sick of making a spectacle out of his legendary death.
In a way I think Kaido wants to surpass Oden by having an even more legendary death. That’s why he does outrageous things now, jumps from sky islands, challenges Whitebeard and wants to start the biggest war the world has ever seen and let himself get tortured so many times.
He used to be cautious and ambitious, maybe it’s a trait he inherited from Rocks D. Xebec, but after witnessing Oden’s death he wants to die in a spectacular way to feel like Oden never really was superior to him in the end.
That’s also why he mocked Momonosuke and got angry when Momonosuke fearlessly told him his name in the last chapter. He was reminded of the way Oden had the upper hand both in battle and being a badass and it hurts his pride to be reminded of it since Kaido values power above all.
Orochi isn’t the only one who’s haunted by Oden’s ghost, Kaido is just as paranoid as him, albeit in a completely different way.
*Theory by AgeofSmiles