I watched Neil DeGrasse Tyson's Masterclass the other day, and he had something interesting to say about this.
https://www.masterclass.com/classes/neil-degrasse-tyson-teaches-scientific-thinking-and-communication?sscid=c1k3_k8maw
At one of his science events, Tyson was confronted by a man who was convinced the moon landing was faked. Tyson went over some of the evidence why that wasn't the case, including the calculation of the fuel on the Saturn V rocket -- being just enough to propel the astronauts out of earth's gravity and to the moon, and then lift the landing pod *back* from the moon into outer space for the journey home back to earth.
The man still wasn't buying it.
Tyson asked the man what single piece of evidence would be enough to convince him the moon landing was real. The man said: Photos of the moon landing site would convince him.
So, Tyson supplied the man with a link to NASA's website, where the public can access photographs taken from spacecraft orbiting the moon which depicted the moon landing site.
The man saw the photographs, returned to Tyson, and said something about NASA being controlled by the government, so none of those photographs could really be trusted.
Tyson replied: I showed you the evidence you asked for, and you're still not satisfied. I'm not wasting any more of my time. We're done here.
Moral of the story: Know when to disengage. You can argue endlessly with conspiracy theorists and still not get anywhere, because they are more emotionally attached to their view of the world than to reality.
I would also say this. If conspiracy theorists applied an ounce of the skepticism they routinely apply to mainstream knowledge to their own claims, their worldview would collapse. A true attitude of skepticism requires questioning all the information you're given: and when you do, the mainstream view of the world suddenly doesn't look so bad.