To waste effort on a futile project.
waste breath
To speak in a manner which is needless or futile; in discussion or arg …
like talking to a wall
A futile or unsuccessful attempt at communication due to the ignorance …
plow the sands
to spend considerable time and effort to do something useless; to wast …
piss money up the wall
To waste money, normally through ineptness in business.
rock the boat
To disturb the status quo or go against rules or conventions, as in an …
hit a wall
To come up against an insurmountable problem.