"Turtle soup" is a phrase that means using something valuable or precious for a purpose that doesn't give it much value. It implies wasting something useful or important. Full definition
The cook toils over mock turtle soup and a chocolate cake covered with green sugar roses, which the hungry band of visitors is not invited to taste. (bookbrowse.com)
Diamondback terrapins, which were overharvested for turtle soup in the early 19th century, have been protected in New York on and off over the past decades. (sciencemag.org)
Turtles in this group dwell in tropical and subtropical oceans; among their representatives are the modern Hawksbill Turtle and the Green Sea Turtle of turtle soup fame. (sciencedaily.com)