You win political influence by being a crucial part of a win. You lose political influence if your political opponents are in office. The best chance to have your voice heard on Israel is being a crucial part of a Harris win.
I would recommend folks watch this 20 minute video on Rules for Rulers from CGP Grey.
Despots, Presidents, CEOs, Deans, Homeowners Association Presidents, the guy who runs the open mic- at the end of the day they have to follow the same rules to maintain their power. The zero'th rule in the video is "without power, you affect nothing".
I'm voting for Kamala, and I'm voting down ballot for any pro-palestine candidate. I want to send the message that in order to get reelected, she will need to change her stance.
When I see people not voting out of protest, they are giving their opposition the influence over their elected officials. Remember, they work for you, and voting is how you let them know what you want.
And your calculations are you get off of losing and even people who agree with you on almost everything aren't good enough to stop you from trying to lose more influence.