Her campaign needed some Bobs
The main problem is twofold
1. Harris herself, but let's assume for now that she had a chance of winning.
2. (Besides Harris herself) The Dems used a half measure when they should have gone all the way.
Joe Biden was a 2-ton anchor tied around your leg while you're drowning, and instead of making it unmistakably clear that she wouldn't be Joe Biden 2.0 she hemmed and hawed (the way she hemmed and hawed about everything else), and even worse, she kept working with the same fucking losers who had been running his campaign, the same people who knew back in 2022 he was in no shape to run again but were arrogant enough to proceed anyway.
I'm not convinced that Harris could have done anything to win, but assuming hypothetically that she DID have a chance, it would have required her to completely purge the campaign of the same morons whose efforts yielded internal polling having Biden losing NEW FUCKING YORK and Trump getting over 400 electoral votes.