bet on the wrong horse
see back the wrong horse.
What’s Wrong With The Word “Addict”?The word addict dates back to at least the 1500s, adapted from the Latin addictus, meaning "assigned, surrendered." But, if experts in drug addiction treatment have their way, use of the word addict as a noun will soon see its end date.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.