The term "white elephant" comes from the olden days in Siam, now Thailand. White elephants were precious but problematic. They couldn't be sold or killed, and they were expensive to maintain. They were like a money pit, where you keep spending without getting much back.
A story says if a king wanted to punish someone, he'd gift them a white elephant, knowing its upkeep would drain their resources. Today, "white elephant" describes costly, pointless projects that waste money.