So, you admit that you think engaging in conversation without curiosity is good actually, and that you haven’t read the rest of my comment. If you had, you might have found this part interesting:

In both cases you can simply point out that they are wrong about what you are saying - because if you had to ask this question then they are usually badly reinterpreting you. You can point out that a curious person would want to fix their misunderstanding.

I also usually say that I am curious to understand them but that I am struggling to and I would like them to answer my questions in order to help. Again, usually by the time I’m asking this, they’ve ignored several direct questions.

I absolutely was not characterising every disagreement as trolling, and if you were curious enough to read the entirety of my comment, you might have noticed this.

I was going to ask what kind of useful conversation you think can be had when someone isn’t curious to understand the other person, but I actually was curious enough to read your comment, and you gave an example. If the flat earther is genuinely curious to understand the answers to their questions - some are and many have changed their views after being convinced - but the astrophysicist is not curious, then the flat earther is the better person in that exchange. The flat earther could be convinced, but not by someone incurious to understand them. The astrophysicist won’t get anywhere by blindly throwing facts at them and expecting them to listen. Flat earthers don’t all believe the same thing, and we’re all wrong about something. If you want to engage someone like that, you need to ask questions and learn what they believe. Without that you can’t help them understand you.

Conversation is a two way street, always. Treating someone like they’re beneath you is not only going to prevent you from understanding them in any way, it will prevent you from being able to communicate back. The loss of curiosity is the loss of thought, of community, of reality, of humanity.