In his introduction, Kaido's main theme was resolving around the fact that you always have to bet on him in a 1 on 1 fight
And we know Oda always love to make Luffy destroy legendary myths like he did with Katakuri's track-record
This is why imo, Oda would at one point make Luffy fight Kaido in a 1 on 1, beat him and destroy this myth around always betting on Kaido in a 1 on 1