The left is every bit as guilty. Spend long enough telling people how stupid and backwards they are and eventually they're going to get tired of hearing it.
The smugly superior routine has backfired, the left enjoyed pointing out how superior they are, and lost most states, then they lost the house and the senate, now they've lost the White House, next will be the supreme court. How much do you guys have to lose before you realize the message isn't working? At what point will you realize that most people don't like being sneered at and will retaliate? Every time you lose you blame everyone but yourselves, then double down on attacking all those stupid people in the next election. As a group, you've embraced an attitude that's exclusionary and insulting, and convinced yourselves that it's the only way to beat the ignorant masses.
The democrats used to have a pretty good platform, but it's been lost in anger, accusations, and splinter groups. The message today is hate Trump, hate Trump, hate Trump, hate Trump supporters, outrage and blame. The party can do better, the dems can take congress in November if they get their act together and come up with a platform that isn't "stop the ignorant fools".