Because the basis of Western democractic justice systems are that we punish people for the crime they have committed, not the crimes we think they will commit.

Because the basis of Western democractic justice systems are that we punish people for the crime they have committed, not the crimes we think they will commit. If we apply this standard for punishment, then anyone (including yourself) could be placed in jail. And then people like you could then say with conviction that you were likely to be a bad person and you deserved it.