A big part of how the left won was by transforming its image.
Go back a hundred years and the left had much the same makeup as it does now. But the image of a typical leftist was ragged, angry and unstable. A ranting bombthrower at best. A ridiculous leafletter at worst. One step away from a criminal. Not at all the sort of person you wanted to be.
And the "sort of person you want to be" is how the left makes over the country in its image.