An idiom meaning a waste of a treasure or talent — possessing something valuable but not using it.
高性能のカメラを部屋に飾って使わないなんて、まさに宝の持ち腐れだ。
Leaving a high-performance camera on display in a room and not using it is truly a waste.
彼の英語力を生かさない会社は宝の持ち腐れだ。
A company that doesn't make use of his English ability is wasting a treasure.
その古いピアノは修理すれば弾けるのに、使われないままだ。宝の持ち腐れだね。
That old piano could be played if repaired, but it remains unused. What a waste.