In all honesty, how can anyone be disappointed? What made them believe there was reason to believe in this guy to begin with? He had no record of accomplishment whatsoever. They should be disappointed in themselves for letting themselves be fooled and manipulated by a snake oil salesman.
Someday you'll be disappointed by someone or something in politics, and somebody will say, "How could you possibly be disappointed? How could you possibly believe in that?" Maybe it's already happened.