One thing I've noticed while talking to conspiracy theorists is they really only know how to have one kind of conversation about them.
They say a thing.
You rebut it.
They say a different thing.
You rebut it.
And it just keeps going.
I've found that if you never rebut it but instead just keep asking them for more info without letting them change the subject they run out of steam.
You can get about 3 questions deep with a flat earther before they get lost and can't continue. 1/3