I was looking at a recent chapter and someone
! Ace mentioned that they intended to make their captain Kaizoku-Ou.
It occured to me though, if you have a crew of any size, wouldn't the odds be in favour of at least one, and possibly several members deciding to betray you at the last moment? The treasure is so awesome as to have practically created modern piracy, and with the right motivation, any degree of nakamaness can be worn down.
Could this torpedo someone like Whitebeard (who obviously has a fairly numerous crew)'s chances of becoming Pirate King?
Who would be the betrayer in the Mugiwara? Nami's the obvious choice, but Robin could be (if it turns out that there's a clash over the historical value of the treasure) or even Usopp (if it's necessary to prove to the world he's a brave man)
How do you defend against this? Send off a single man in a small boat to Raftel? Attempt to vet and purge your ranks the closer you get?