Pyrrhic Victory

Pyrrhic victory \PIR-ik\, noun:
A victory achieved at great or excessive cost; a ruinous victory.

As in, "He rose to the top of the corporate ladder but it was, at best, a Pyrrhic victory, having neglected his family and his health."

"A Pyrrhic victory is so called after the Greek king Pyrrhus, who, after suffering heavy losses in defeating the Romans in 279 B.C., said to those sent to congratulate him, "Another such victory over the Romans and we are undone."