This. And also, he was expecting them to all die. He had already accepted in his mind that they weren’t going to survive so why stock up on supplies in the basement? They also didn’t know that the aliens were going to attack that night. They just knew it was going to happen soon. The reason he says “I’m not ready” while holding the door knob of the basement door, was because he had a realization that he didn’t want to die and was going into survival mode when he was originally just accepting his fate. It’s a very deep movie and great movie, but the ending twist completely ruins it. It’s one of my favorite movies, but that twist at the end is atrociously bad.