Kaido is an alcoholic so already he cannot pull off self discipline at all (note that Zoro is a heavy drinker but not an alcoholic, he’s never even been shown actually drunk before).
Kaido is also a pirate and he can’t stop being one so already honor and justice are out of the window since his form of piracy is clearly incompatible with such things. Kaido cannot become a samurai even though he admires them so he just cheats and jumps to great legacies in death that Samurai achieve even though it’s impossible to get the legacy without the actual Way of Samurai itself.
It’s even interesting that Ryuma, a samurai, exists as one of the oldest characters known by name in the verse because his legacy was so great yet Rocks, Kaidos’s former captain, from just 40 years ago is practically an unknown in the verse.
Interestingly, Ryuma is not only remembered for his strength but his sense of justice in protecting Wano while Rocks could’ve easily been the strongest in the verse but his supposed heinous crimes were so severe they were wiped from history. And this isn’t even just a World Government thing, Joy Boy still has a legacy despite the Government trying to silence him too so if Rocks was really worthy, he would’ve had a real legacy as well.
But Rocks wasn’t (even Teach who supposedly carries this legacy WILL FAIL because it’s a bad legacy from a bad man). He was an unjust man so when the Government silenced him, he was truly silenced. Unlike just men like Ryuma, Joy Boy or Roger.
This is a very interesting idea Oda is doing with New World villains. Giving them seemingly great ambitions but giving them severe character flaws that make their ambitions impossible. Big Mom wants racial equality but ONLY through her eyes. Hody wants to stop Fishmen oppression but by race wars. Doflamingo wants to destroy the Celestial Dragons but by killing everyone so the Celestials have no one to rule. Kaido wants Great Legacies in the deaths of good men but he’s a bad man and doesn’t realise bad men don’t get great Legacies in this verse.
*Theory by ImmaIvanoM
