I appreciate your effort and thank builderofcastles (destroyer of reason) for bringing my attention to it so I could upvote you. But I advise you your efforts are futile. The flatearth thing is not about facts, evidence, logic - it's about retreat from reality. These people do not want to face reality, it is an inconvenient truth. The only conspiracy theory is in their minds - in fact they are the source of the conspiracy: of denial of reality, of irrational behavior, of delusional thinking.

Every "proof" they have is sitting on top of one or more alternative facts or fallacies, and as so as you remove one argument they prop another beneath it. Meanwhile they sit behind their computers (powered by the fruits of the same science that proves them completely wrong) laughing at you and the time you're wasting. Nothing except complete exile to a life without any scientific advancements would ever tempt them to admit they are wrong.

In the mean time (because exiling crazy people is somewhat shunned by polite society) maybe that crack squad of NASA conspiracy agents should quietly sneak into their homes and reprogram their GPS devices to work on the flat earth model. Then we just wait for them to drive off a cliff, or into a brick wall. More to the point, if they really believe the BS they waste your time with they should do that reprogramming themselves. If they did I'm sure they could sell such devices for a fortune to all their friends. But they don't believe it, so they don't do that and they haven't gotten rich selling a flat-earth model GPS. Or launching a flat earth satellite. Or a rocket that just needs to fly 3000 miles to land on the sun (which must be just a big yellow cold disk or we'd all be dead).

Their inaction on their beliefs and their reliance on the facts that are contrary to them speaks volumes for their conspiracy of deception and denial.