Seriously, it's plain as day with a material analysis. The material conditions for the working class aren't improving either way, but the party with red hats have a (wrong) solution, to blame immigrants and the gays. People falling for fascist rhetoric are miseducated (yay American education system), disillusioned and desperate. A competent and well meaning political party could turn that anguish and contempt for the status quo into results, but Dems are neither of those things. In the end, they also serve capital.

To meaningfully reform healthcare is to make workers less desperate, it will allow disgruntled and abused workers to leave their workplace and therefore dilute the power of the employers and to take away from the pharmaceutical companies. To meaningfully push through higher wages is to take away from capitalists at large. To meaningfully reform housing is to take away from landlords. To meaningfully reform prisons is to take away from the private prison industry. To meaningfully stop the genocide in Gaza is to take away from the Military Industrial Complex. They'll promise and pay lip service to those things but will never meaningfully change them.

They are not well meaning. One of the few aspects in which they are better is abortion and they fumbled that so hard, because they're also incompetent.

But no, to the diehard libs, it's because half the country are mentally ill. That's the only explanation.