Chances increase dramatically if we cooperate in testifying against the perceived "mastermind", as Ms. Ellison did.
There is a lot of room for manipulation in the justice system in determining the hierarchy and who gets to be offered a sweet deal. Had Caroline been labeled by the media as 'the mastermind' and Sam as 'the help' by the media, the outcomes may have flipped.
The media could totally construct a story where Sam was just the helpless front guy who knew nothing, misled as to the source of the money which Alameda Research was providing.
It’s also not strictly he-said/she-said; there were at least two other executives who knew what was going on, both of whom implicated Sam as the mastermind.