The aims of this study were twofold, to: (1) examine the behavior displayed by participants who expected to be nominated for donor roles in dictator games wherein initial endowments of players are determined by lottery and (2) investigate the conduct of donors who were confident in their good fortune in relation to their power as they redistributed the rewards they had gained. Results from a dictator game in which a donor is accorded the absolute power to redistribute initial income and a random dictator game in which both a donor and a recipient declare their redistributive preferences and one of them is selected randomly by a computer were compared. Confident donors made more self-serving redistribution decisions than did unconfident donors in both games, but the difference was clearer in the dictator game. In relation to their preferences exhibited before being informed of their roles, confident donors decreased their redistribution amounts after discovering their roles; the decrements in the dictator game were conspicuously larger than those in the random dictator game. In short, confident donors were greedier than unconfident donors; the difference became more pronounced when their redistributive power was unconditional even though their confidence had no rational basis.