Ironically, that was one of the biggest campaign points and voter sentiment on which people flipped to Red. We all know what happened.
If I beg you to reconsider on a very serious issue that is in your power to change stance on, and you not only ignore me but laugh in my face, then why exactly do you still get my vote? Why exactly should I reward you for completely ignoring my protests?
Make sure to swap Gaza for your single issue - maybe LGBT rights, or abortion, or gun rights - and then seriously think about how you would deal with it.
The Democratic party has basically decided to lean on “but they’re worse” as a political platform while backsliding on multiple issues. They do this because Democrat voters lap that shit up, chant “vote blue no matter who” like members of a cult, and then cry out in astonishment when the Democrats in Congress and in the gov keep sliding towards the right.
Also, an addendum: before blaming abstainers and third-party voters, it might be good to ponder on why Democrats preferred risking losing the presidency over making any concessions whatsoever on Palestine. At best, it was a grave miscalculation borne out of hubris. At worst, it was an act of self-sabotage to ensure unconditional support for Israel. Pick your poison :)
1) threaten the international rules-based order, shattering the expectation of adherence to any number of human rights-centered protocols and representing crisis that can snowball into larger conflicts,
and 2) are often facilitated in part by police actions (civilian detainment, censorship, killings dressed up in lawful rules for the use of force, etc.), which threatens a general spillover of military action into the civilian/domestic status quo.
In other words, tolerance of genocide leads to a general shift towards war and despotism, even for people who aren't in the group targeted for genocide. Tolerance of evil builds the scaffolding for further subjugation.