I suppose I am fortunate that I don't know anybody who is that far gone that cares deeply about me.
However, the people I use this trick on aren't strangers. They are regular acquaintances that have conspiratorial views, but think I am one of the "good" ones. When these people tell me things like it's just a difference of opinion, you can tell that they derive strength and satisfaction from their ignorance.
My goal isn't to convince them, it's to stop them from reaching into their bag of conspiracy theories when talking to me. In that, it has been wildly successful.
I can see that your approach would be effective at shutting down conversation and stopping people from telling you their wild conspiracy theories.
I think that with my experience, I've had to recognize how fragile some of the most important incentives are. Like the safety that underpins trust. To have trust, it needs to be safe for people to be wrong. That means I often have to listen respectfully to views that I find abhorrent, in order to get to the point that I can share my own thoughts fully.