Unfortunately they don’t have to make people stupid. They already come that way. If you figure be definition half of the populace is below average in intelligence, and the Democrats get about half of the vote you can figure out which half voted for them.
As the late Terry Goodkind wrote: “People are stupid. They will believe a lie because they want to believe it’s true, or because they are afraid it might be true.”
― Terry Goodkind, Wizard’s First Rule
Explains the many false beliefs of Democrat voters - climate change, the proliferation of imaginary genders, EVs being superior to gas vehicles, etc.
Bkmk