Both sides probably really do believe they're going to win tonight. And in a few short hours, a lot of partisans will feel an exquisite form of existential grief.
I'm reminded of some interviews I did working on my book, White House Ghosts: Presidents and Their Speechwriters. A couple of George H.W. Bush's speechwriters recalled for me the moment they knew it was over. "When you're in the bubble...you feel momentum and the crowds are lively and you know in the outside world you're behind, but in the inside world, you're thinking, 'This is going to be 1948 all over again,'" Steve Provost, Bush's last top speechwriter, told me.
He knew it was over when a colleague pointed out to him that the president had a new Secret Service detail—the first detail was flying to Little Rock to join President-elect Bill Clinton.
Provost worked with Bush on his concession address—Bush edited it more than anything Provost had written for him. "We got in the motorcade," Provost recalled 15 years later. "We went in and he gave it that night and—ah—it hurts just even talking about it."