And yet, if there was ever a time where that isn't worth it, it's when fascists have a high chance of winning. Trump is not a right wing liberal; he wants to destroy the liberal world order that America controls just so no one can threaten his dictatorial power at home.
That may seem like it could benefit leftists elsewhere, but he wants to go to war with neighbors and bully other countries even harder than the liberal empire did. Where the American empire leaves, the Russian empire will take its place. All the while, an old man with no desire to leave a lasting legacy for his family or country is in control of the most powerful war machine on earth.
Literally no. If they were gonna vote Trump instead but decided to go with Harris, their vote is worth the same as someone who would always vote Harris or the vote of a leftist who decided on damage reduction.
Any voting system flattens our personal motivations into a single action. Any statement you're looking to make is moot unless you have a massive campaign to make it clear outside of the ballot box. Even then, the establishment can downplay and misinterpret your motivation as not being representative or as less important than what they want to believe.
There's no better way to translate our will into results. Any system that doesn't use free and fair voting can be tainted and colored by bias, making it impossible to ever undermine the will of the establishment. They will always choose to believe whatever is most convenient, but votes can deliver a reality shock that forces them to adjust their behavior, even if they never change their minds. The only other thing capable of that is violence.
Your motivation doesn't matter, only the result of your action.