The Russians didn't start this brand of insanity in the US, it has been a cornerstone of Republican policy for the past ~12 years. (And has been present, on a lower-key note, for the prior 20. The toxic culture war isn't anything new - Reagan was fighting it against homosexuals[1] and welfare queens 40 years ago.)

It's a monster of our own making. When politicians start courting that fringe, you get a virtuous cycle, where the fringe starts impacting policy, which emboldens and encourages more and more radicalization.

[1] Look at the rhetoric surrounding the AIDS epidemic, and tell me if anything has changed.