>>213366863 (OP)That's part of the Trickster God stuff OP, in this case the Trickster God fuses with the MC. When the villain puts on the mask he tries to do real shit and we sense it would be horrible if he got into a position of real power, but the movie stops that. The character is basically acting on his emotions in a simple cartoon character way, which is the point.
Something similar happens in Swamp Thing. The characters take a magical serum and it brings out "who they really are", good or bad.