Democrats who ignored all the warnings about how failing to represent their constituents would result in a loss allowed republicans to take power. Not that democrats ever wield it when they have it.
Undocumented immigrants, when democrats permanently adopted republican border policy for a stupid momentary gotcha.
Trans people, when democrats not only said nothing, they actually ran anti-trans hate in their own ads.
Palestinian Americans. This has to be obvious even to you.
Women, when democrats preferred to keep the filibuster over codifying Roe.