First of all, at this point people in the US should vote against Trump for their safety, and that means in the current political system they have to vote for Harris. That's the reality they have to face. The Trump party has made fascist announcements that are real and people should expect them to be made into real actions.
The problem is that the Democrats frankly have abysmal messaging and are drifting to the right further and further while using Trump as a threat to their voters. They adopt anti-immigrant policies and are distancing themselves from pro-LGBT stances, saying it's the states decision. Both these issues as well as demands for a ceasefire poll exceptionally well, but the Harris campaign seemingly don't want the edge. With all this they are signaling that right wing worries about immigrants and trans people are valid, although that's absolutely not the case, and leave people to decide for example "do I want anti-immigrant light or extra harsh anti-immigrant?" when everybody says immigrants are an issue. This is unacceptably stupid and risking the vote. And that's ignoring the elephant in the room that progressive policy like health care is exceptionally popular and using that as counter messaging would win her voters.
We've seen how popular the Democrats got after Harris took over and Walz got nominated. It signaled change. Now all the Democrats say that it's gonna be the same old as usual treading on and the same bad argument vote us or you'll get a dictatorship. I'm not denying Biden dropping out had nothing to do with the surge of popularity, but back then we also had comments like here, basically declaring any dissent from supporting a decrepit old man as the candidate as heresy. Now there are again, only Yes men here saying if you criticize Harris you're a bot or a Trump ass eater. What is wrong with you?
Finally, I have the creeping suspicion that Democratic establishment people don't fear a fascist Trump administration themselves personally as much as the population has to. Trump announces he will go after his enemies, Latinos and trans people (probably all queer people actually). He has anti women's health and rights messaging all over his campaign. But that doesn't seem to be a risk for people higher up in the party. I suspect that when you're rich you don't have to worry about abortion bans or HRT access. And if Trump threatens them with violence they always have money they can throw at him. It's much more comfortable to run a risky neo liberal and right wing platform against a fascist if you can jump ship later on.