Actually that's not the root cause of it. As much as I don't want to, we can blame it on the King James version of the Bible which so many Christian Bibles are based upon and the subsequent "supposed" translations of the Book of Enoch which appear to be written by the same people that made the most popular mistranslation of everything YHWH and his Son YSHUA ever said.
Because Genesis talks about a firmament and because enoch talks about the course of the sun and the moon, people who want to believe the wrong thing "this is called believing a lie" choose to believe that Enoch being a wise old man because he lived so long and was God's favorite before Noah wasn't a babbling fruitcake. So when says something is following a course in the sky they want to assume it is meaning that they are attached to monorail like tracks and dangling from said tracks like a sky tram above us, that said tracks are attached to the firmaments which they like to call crystalline structures.
When you confront them about these sky globes and say "how do meteors get through" they always say "those are pieces of the globe breaking apart" and that the breaks came from when "the demons were cast down to the earth, thus making holes that are now disintegrating".
Personally, I think that flat earthers in their ignorance are taking away from the ultimate and unlimited power of God when they do this.
The rabbit hole goes deep and it is likely Satan's greatest masterpiece next to a false religion of which he has created many.
The Bible also says that God hung the earth and the stars on nothing. They skip that one. If we can observe all the other celestial bodies and see they are all spherical, then why would we be the only fools on a flat planet. I think that flat earth theory was an experiment to see how easy it is to make people believe anything.
I made this post earlier asking for help proving these nut-jobs wrong. Perhaps you can get it out to your people and we can put an embarrassing end to this joke called The Flat Earthers Movement. https://steemit.com/flat/@kreezxil/proving-the-earth-is-round