I understand why people are upset at how Kaido is taking this much damage, but I think it makes perfect sense.
We know very little about Kaido aside from what we were told during his introduction.
What Wano as an arc has done is highlight a very important relationship Kaido has had that still effects him to this day. That relationship is Kaido and Oden. One of Kaido’s defining character features is his scar. The only scar that was given to him throughout his years of battle, a scar given to him by Oden.
The narrator told us “if it is one on one bet on Kaido”, but if you look at how Kaido vs Oden went down Oden had Kaido dead to rights before Higurashi interfered.
Kaido couldn’t beat Oden one on one and needed outside help to finish the job, a true stain on his reputation. He not only lost his reputation of invincibility when he fought Oden but he was also brought down to the most vulnerable state of his life as far as we know. Kaido was so annoyed at this outcome that he had the interfering party killed.
Fast-forward to Oden’s execution, Kaido humors Oden’s request for mercy by giving him an hour in the pot. Any normal person would die instantly but not only did Oden persevere but in one hour he was able to regain the trust of the Wano populace that he spent 5 years ruining.
