They can be dumb as a box of rocks but they are deluded into thinking they are smarter than you because their elites use that as a talking point.
Everything to do with liberalism/“progressivism” can be understood if you keep two things in mind: 1) Liberalism exists because libs enjoy being sinful degenerates and their singular political focus is on changing society to give license to their degeneracy, and 2) Libs are emotional children, which is why when you try to have a rational debate with them they react irrationally by freaking out or calling you the adult equivalent of “Poo-poo head.” The fact that such immature individuals believe themselves to be your intellectual and moral superiors is just conclusive evidence of the depth of their self-delusion.