We investigate corruption as a social dilemma by means of a bribery game in which a risk of collective failure is introduced when the number of public officials accepting a bribe from firms reaches a certain threshold. We show that, despite the social risk, the pursuit of individual interest prevails and leads to the elimination of honest officials over time. Reducing the size of the groups while increasing the probability of collective failure diminishes the public officials' corruptibility but is not sufficient to eliminate the tragedy of corruption altogether.