I've always understood that phrase as implicitly beginning with "Ceteris paribus, " and ending with "more often than an irrationalist in the same circumstances." Which is to say, if you're somehow forced into the position of playing Russian Roulette with 5 barrels loaded, or trying to create AGI which won't destroy the world before it's too late, you're probably going to lose. But you should do so with lower probability than someone with the same resources, using them less rationally.