Then tell me why it's common practice in the court system for both prosecutors and defense attorneys to question the veracity of a person's testimony on the grounds that the person has something to gain? A good example is when an accomplice testifies against his buddy for a reduced sentence for himself. The testimony isn't rejected outright, but the jury is encouraged not to give it as much weight as tesimony from an unbiased source. It appears the justice system doesn't share your view on argumentum ad hominem.

Dakota