I am completely with you. There's absolutely nothing I can do to prevent what is going to happen to the Palestinians. I did what I could to prevent it. But I'm still going to lament it.
At the same time, one may plausibly hope that there is something constructive that comes from people seeing the (very, very foreseeable) consequences of their voting behavior. And perhaps that would provide some benefit going forward, which is worth cheering for.
It may be true that @BrickHorn is sitting there wringing his hands over the fate of the poor Palestinians. And meanwhile, @Brisketexan is maniacally finger-tenting while hissing "excellent." And they have the exact same impact on what is going to happen in Palestine. When the time for deciding what was going to happen in Palestine was upon us, they were on the same side.
But that time is gone, and they're both now equally impotent. The hand-wringer's hand-wringing over the finger-tenter's sinister grimace is a bit stupid. As is the finger-tenter's supposed glee, I suppose. I imagine they're both coping mechanisms. I suspect neither will be terribly effective in the medium- or long-term.
That's why we have alcohol.