The reason why the arrests have not happened yet is because a citizens arrest on such a grandious scale requires strong evidence that can prove Bush guilty beyond reasonable doubt. Even with the atrocities of the Iraq war,  is still not enough evidence that it was done for personal gain So more evidence has to be collected to prove him guilty (such as a secret document confessing the conspiracy) . If one minor fluke happens in his arrest h, we would be charged for holding him hostage.