young invincible
n.— «In the parlance of the health care industry, Ms. Boyd, whose case remains unresolved, is among the “young invincibles”—people in their 20s who shun insurance either because their age makes them feel invulnerable or because expensive policies are out of reach.» —“For Uninsured Young Adults, Do-It-Yourself Health Care” by Cara Buckley New York TImes Feb. 17, 2009. (source: Double-Tongued Dictionary)