well they will still only be able to see one side of it at a time, in their minds they will still think it’s a circle, not a sphere, so you can’t fix stupid.

There was that one guy who built steam powered-rockets and claimed to be a flat earther then died https://en.m.wikipedia.org/wiki/Mike_Hughes_(daredevil)

To be fair, his PR team said (after his death) he only made this claim to attract funding. Make of that what you will

They’ll crash into the firmament at high speed, and die. God will probably smite their corpse for doubting Him.