Winning elections constantly and a seeming inability to lose them tends to make one arrogant.
I'm surprised that people feel Democrats have reached the level of arrogance Republicans only reached after 8-10 years of power in Congress and they believed that the 55-45 red state/blue state thing was a long-term lock. There are always going to be some individuals who don't get election data patterns and will draw conclusions from ignorance, but that seems to be different from what people are claiming.
If your side wins elections in spite of having screwed up or proven itself corrupt, that's when arrogance enters. It comes in on the back of contempt for the voters.
I also think that predictions of Democratic hegemony stretching into the future are no more muddled by wishful thinking than predictions that Democrats have entered decadence already.
