Randall G. Holcombe argues that "Firms might prey on their competitors' customers, as competing mafia groups do, to show those customers that their current protective firm is not doing the job and thus to induce them to switch protection firms. This action seems to be a profit-maximizing strategy; hence, protection firms that do not prey on noncustomers may not survive." Holcombe states that mafias offers protection for a fee, but it also uses its resources for predation; and thus profit-maximizing firms could be expected to employ them in the dual roles of protection and predation. Peter Leeson and Edward Stringham rebut this argument by claiming that unless the firm were overwhelmingly more powerful than its prey, it could incur substantial costs and risks in attempting to extract wealth by force. They argue that the potential for even a small state to inflict losses on a larger state explains why violent confrontations between states are less common than between individuals in New York City's Central Park; in other words, it is not the size of the group in question that matters, since in either case being the aggressor is likely to bring about undesirable risks and diminution of resources.