It's more complicated then just saying leverage. Again, if one reads the book you will see that "both" the main players were actually "trying" to force the other out. In other words, leverage was not used simply to juice returns or average into a loser, the leverage used by both Arnold and Hunter were used to squeeze the other. Arnold was smart and that he gave Hunter the impression he was all in and even sent out some false rumors that he was on the edge of liquidating. He was lying. He had plenty of ammo left and when the time was right, he moved all in and swallowed Hunter whole. It truly was a game of poker and trying to read the other player.
So basically it was leverage .