trophy kid
n. A child who grew up getting praise and trophies just for participating in activities, and now expects esteem and rewards as an adult.
Examples
2013
Author Ron Alsop calls them "trophy kids," a term that reflects the trend where "mere participation is frequently enough for a reward," and being overly praised for little accomplishment.
—Marie Engen, “The Plight of Generation Y,” Boomer & Echo, September 24, 2013
2012
Yep, we’re talking about Generation Y — loosely defined as those born between 1982 and 1999 — also known as millennials. Perhaps you know them by their other media-generated nicknames: teacup kids, for their supposed emotional fragility; boomerang kids, who always wind up back home; trophy kids — everyone’s a winner!; the Peter Pan generation, who’ll never grow up.
—Emily Matchar, “How those spoiled millennials will make the workplace better for everyone,” The Washington Post, August 16, 2012
2003 (earliest)
One very astute father once said to me, "Jim, I've got it. There is a huge group of trophy kids growing up today who won't have the character and resilience to compete in the labor market."
—Jim Fay, “Make Your Kid Responsible For Their Actions” (PDF), Love and Logic, October 13, 2003
Notes
This phrase had a different meaning a dozen years ago when I posted it as trophy child and defined it as "a child used to impress other people and enhance the status of the parent or parents." The logical (and not even remotely surprising) lesson here seems that some kids raised as trophies expect to be treated as trophies when they become adults.