In discussions of all kinds, one frequently hears someone declare that there is no point in continuing the conversation, because their interlocutor will never be convinced. This sentiment can sometimes be a kind of short-hand for various understandable reasons to cut off a conversation — your interlocutor doesn’t seem to be taking you seriously, they are trying to catch you in a contradiction or otherwise make you look stupid, they are just trying to waste your time, they just want to repeat the well-worn formulas that for them count as “opinions” or “views,” etc. — but insofar as we take it literally, it is a terrible reason to stop conversing.
The point of a conversation is not to convince as many people as possible to adopt your viewpoint, nor indeed is it to find good replacements for one’s own views. We are, at least sometimes, rational beings, and as such, we have a duty to give reasons for what we say.
There are circumstances that supply a good excuse to shirk that duty, and we are of course free to shirk it arbitrarily if we so choose — no one has infinite time or patience, and sometimes the interlocutors who are genuinely asking in good faith and with an open mind are the most exhausting of all.
Yet it is never acceptable to cut off a conversation because you have determined that your interlocutor will never abandon their views and adopt yours. It is perfectly acceptable, again, to conclude that they’re not taking you seriously, that they are just waiting their turn to say the same things they would say no matter who they were talking to — or indeed that you’re simply getting bored. But if the only thing that keeps you from becoming bored with a conversation is the prospect of getting someone to abandon their own view and adopt yours, then you have failed as a human being in a fundamental way.