Also, what's the use of. What purpose or advantage is there in, as in What's the good of crying when you can't do anything about it? or What's the use of getting a doctorate in philosophy when you won't be able to get a job afterward? This idiom was first recorded in 1701.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.