Kid “You BETTER Win”.
I don’t understand why people assume Kid has lost his ambition based on his comment in the last chapter (you better win). Kid already gave up the fight with Kaido to take on Big Mom ,an equal enemy, 16 chapters ago. Not because he thought he was inferior to Luffy, but because at a certain point Kid started being more of a team player and he accepted Luffy was in a better stance to take on Kaido because of his ryou. A specific skill particularly suited to deal damage to Kaido.
After seeing Luffy save Killer, Zoro sacrifice his body for others to survive, and Law save each of them on the roof in multiple occasions. I’m sure he became much more willing to be cooperative with his fellow super nova. They made a plan to separate the yonko in order to improve their chances, and his role in that plan was to take on a yonko along with Killer and he was even excited to take Big Mom 1v1 before Law showed up.
Also keep in mind that when he left the roof it was still a 2v1 against Kaido ( Luffy was unconscious ), and that Kid is currently fighting big mom while taking unavoidable damage from Hawkins.
It’s not like he’s accepting Luffy as superior this chapter by saying he better beat Kaido. He just recognizes that they have different opponents and he is holding Luffy accountable to doing his part while he does his.
We the readers know Luffy is obviously stronger, but Kid’s confidence and competitiveness hasn’t changed. This is still the same guy that took a direct punch to the face by a yonko and smiled.