After a day and several replies from people. I've come to the conclusion that people here are ok with their party and leaders supporting genocide and they attack the questioners (instead of their party leaders) who criticize those who support genocide. Critical thinking is scarce here.
I'm shameful of humanity.
Local politicians > work way into DNC primary machine > work to change how the primaries work > reduce ability for $ and top brass to pave way in primaries for their chosen people > get candidates we actually want winning primaries. It's a long game.
If you're asking me how to get Kamala Harris herself to change course on all this immediately, I have no idea. But witholding your vote isn't going to sway things, either. Even if we got every leftist in the country to not vote in solidarity - that wouldn't be enough. There's not enough of us yet. That's the reality of working within a democracy, you need enough people organized to vote. But you need time and an actual strategy WELL BEFORE THIS STAGE OF THE ELECTION CYCLE. All that would do now is spoil the election, give it to Trump, and that very well may end democracy in the US as we know it.
Regarding "guaranteed leftist votes" you must consider that the opposite also applies. Why would Kamala Harris care about your views if you're never going to vote for her? (Maybe you would if she vowed to save Palestine and forego allyship with Israel until they stop genociding, though, which is fair. But a lot of folks out here making these arguments are not doing so in good faith.)