Imagine Kaidou knowing the whole story like Roger and Rayleigh, the whole story of the lost century, a play, Joyboy, everything the government fears...
Not only would he be feared for his superior strength to Roger, but also his generosity would be raised to heights never seen before.
His achievements in combat make his bounty of 4.6B easily rise to 5B (made in Wano), with the boost the government would give to the man who knows all of history would easily be increased to 6B+
I hope that Rayleigh, who is the first mate of the Pirate King who knows the whole story (lost century, Joyboy, ancient kingdoms, etc...), is in houses 4B, otherwise it would be disappointing that even getting the boost that the One Piece offers it not yet in 4B.
But remember unlike Rayleigh or Roger, Kaidou has 4.6B without having found One Piece and without "knowing the whole story"... And your reward is purely based on your strength alone.