러 하다

why bother doing that?

Every line here is the same phrase: 뭐 하러 followed by 하다. "-(으)러" marks purpose ("in order to"), so 뭐 하러 literally asks "to what end?" — and in practice it is a dismissive "why bother": why demonstrate it, why bring that up, why film something we're going to cut, why strike, let's just settle. It is a rhetorical question, not a real request for a reason, and it is blunt — fine between friends, rude to a stranger.

Register: blunt, casual