https://twitter.com/user/status/1270870016066351104
This thread lays it out perfectly. Almost twenty examples, all with links, are given for why a non Trump voter might call a Trump voter stupid. The conclusion provided is that calling a Trumper stupid is being charitable. If Trumpers aren't stupid, then their support for Trump makes them bad people, far worse than stupid. I myself prefer the stupidity explanation, because the alternative is far far scarier.