There are several reasons, that Dems apparently would rather just ignore and make excuses for than acknowledge. Here’s my take:

First, and foremost I think, is that neither of these two candidates won a primary. Harris was selected by a president with dementia and foisted upon the country and Hillary’s primary was rigged, a fact later admitted to in court when the Democratic Party was sued over it.

Secondly, both Hillary and Harris followed Democratic presidents whose records left their constituents vastly more impoverished. In Hillary’s case, it was Obama’s decision not to address the Great Recession in a meaningful way for the poor and working class as well as the foreclosure crisis. In Harris’ case it was Biden’s decision to ignore the affordability crisis and rampant inflation. In both cases Donald was the candidate of change, and people wanted change.

In Hillary’s case, there was also the problem of evident corruption, made public via James Comey and Wikileaks.

Lastly, both Hillary and Harris came off to voters as “electable” scripted and inauthentic, and particularly in Harris’ case, there was a clear effort to stage manage every single appearance and her campaign suffered for her desire to be so controlling; whereas Donald went on a media blitz for the entire campaign and appeared everywhere he could, and despite saying a lot of dumb shit, he came off as authentic. (and thereby, more trustworthy, because it was abundantly clear he wasn’t trying to hide himself)

If you honestly think Harris and Clinton lost because they are women and/or black, that’s your right, but I don’t think that point of view stands up to facts. It’s particularly true in Hillary’s case, given that she won the popular vote. The answer as to why they couldn’t beat such a despicable man is that they are shitty candidates who ran shitty campaigns.