back the wrong horse 下错了赌注；看走了眼；作了错误的决策

【例句】
In all his years as a book publisher, he rarely backed the wrong horse.
做了多年的出版商，他很少有看走眼的时候。

I certainly backed the wrong horse when I said Clippers would win the championship.
当我说快船队能赢得冠军是，我真是看走了眼。