Sunk cost fallacy. They will ride Trump down to the depths of despair, because that's who they are! If they really wanted to win, they would jettison Trump now, but they are too afraid of the "base" to do that. It will be their undoing.

BTW, have you heard the rumor that Democrats are trying to broker a deal with some moderate Republicans to switch sides and give them senior leadership roles in exchange? All it would take is the five or so seats that the Republicans are expected to control the House with. Not sure it's a real rumor but it could really blow a hole in the MAGA party for good if that's the case...