Harris was no more of a crap candidate than Biden was in 2020.

Biden was able to get away with it in 2020 coming off Trump's first term and the shitshow that was COVID's handling under his leadership. Harris didn't have this benefit, being second in command in the incumbent regime, was unable to capitalize on any of the points the Biden administration could claim as wins, while stubbornly refusing to put any distance between him and herself on his unpopular stances. Add in that this was occurring while popular sentiment was clamoring for an inspiring campaign that wasn't the usual DNC paint-by-numbers, march to the right campaign of, "Well, actually, while I can appreciate Hitler's passion for the arts, animal welfare and the health risks of smoking, you'll find that we, uh... disagree about the best way to deal with the Jewish question. Thank you, you're seen and heard, even you Jews out there. Vote for me, 'cause the other guy's Hitler, and I'm not entirely Hitler."

The entire Democrat effort (or lack thereof) was a massive unforced error on their part. Instead, they keep sidelining any candidate who seems to actually excite people and inspire them with hope for the sort of systemic change they want, unless they find they can eventually drag them into their usual shenanigans.

Personally, I think they'd also do best to drop their tokenism with candidates that trot out the same means-tested policy drivel. Rather than go harder on the adjectives next time and hope people show up to vote for, "The candidate who would be the country's first female, Chinese, Navajo, amputee, Leprauchan president in history," have policies that don't include the means-testing and would broadly lift up the working class and poor voters, while also addressing historic inequalities for the many groups that have been disadvantaged and/or excluded from US society for its history. You can tick all the diversity boxes you want with the candidates, but it's patronizing to think people will blindly fall in line for such a candidate assuming they'll represent them, when we've seen that it's mere lip-service paid to very real issues impacting the lives of millions of Americans, which will be promptly forgotten upon taking office, if it lasts that long.