Grump said all of these things before getting elected, but he also said their exact opposites as well. That he can say blatant lies while having a "charisma" such that people hear what they want to hear is exactly how a con man operates. Hence, they were conned.

However, the responsibility still arises as half of their fellow citizens were telling them that they were being conned. But rather than listening to the critics they actively remained ignorant while gloating about "liberal tears" and so on.