I think part of the issue is that after winning on the platform of "change", Democrats veered hard into "establishment status quo". They won so hard that most people don't even recall the few bad parts of the Obama presidency at all (the point of my last comment, that it wasn't all sunshine and roses), and then threw that lead in the trash.

They had a chance with Sanders, but threw away an absurd amount of public goodwill by very openly pushing him out of the running in favor of Clinton. That effectively left Trump as the only candidate carrying the "change" flag, and a lot of people were too dumb to see he was full of shit.

When Democrats had a chance again, they went with another "establishment safe" choice and only won with Biden due to an immense outcry against Trump. Then they lost again because they wouldn't platform someone people were willing to get out to vote for.

If we get out of this shitshow, I'll be very interested in what history says about the last few presidential races.